#+title: Modus themes for GNU Emacs
#+author: Protesilaos Stavrou
#+email: info@protesilaos.com
#+language: en
#+options: ':t toc:nil author:t email:t

#+macro: stable-version 1.2.0
#+macro: release-date 2021-03-04
#+macro: development-version 1.3.0-dev
#+macro: export-date (eval (format-time-string "%F %R %z" (current-time)))
#+macro: file @@texinfo:@file{@@$1@@texinfo:}@@
#+macro: space @@texinfo:@: @@
# The "kbd" macro turns KBD into @kbd{KBD}.  Additionally, it
# encloses case-sensitive special keys (SPC, RET...) within @key{...}.
# I got this from the Org source code.
#+macro: kbd (eval (let ((case-fold-search nil) (regexp (regexp-opt '("SPC" "RET" "LFD" "TAB" "BS" "ESC" "DELETE" "SHIFT" "Ctrl" "Meta" "Alt" "Cmd" "Super" "UP" "LEFT" "RIGHT" "DOWN") 'words))) (format "@@texinfo:@kbd{@@%s@@texinfo:}@@" (replace-regexp-in-string regexp "@@texinfo:@key{@@\\&@@texinfo:}@@" $1 t))))

#+texinfo_filename: modus-themes.info
#+texinfo_dir_category: Emacs misc features
#+texinfo_dir_title: Modus Themes: (modus-themes)
#+texinfo_dir_desc: Highly accessible themes (WCAG AAA)
#+texinfo_header: @set MAINTAINERSITE @uref{https://protesilaos.com,maintainer webpage}
#+texinfo_header: @set MAINTAINER Protesilaos Stavrou
#+texinfo_header: @set MAINTAINEREMAIL @email{info@protesilaos.com}
#+texinfo_header: @set MAINTAINERCONTACT @uref{mailto:info@protesilaos.com,contact the maintainer}

#+texinfo: @insertcopying

This manual, written by Protesilaos Stavrou, describes the customization
options for the ~modus-operandi~ and ~modus-vivendi~ themes, and provides
every other piece of information pertinent to them.

The documentation furnished herein corresponds to stable version
{{{stable-version}}}, released on {{{release-date}}}.  Any reference to a newer
feature which does not yet form part of the latest tagged commit, is
explicitly marked as such.

# Current development target is {{{development-version}}}.  This manual was
# built on {{{export-date}}}.

#+toc: headlines 8 insert TOC here, with eight headline levels

* COPYING
:properties:
:copying: t
:custom_id: h:b14c3fcb-13dd-4144-9d92-2c58b3ed16d3
:end:

Copyright (C) 2020-2021  Free Software Foundation, Inc.

#+begin_quote
Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License,
Version 1.3 or any later version published by the Free Software
Foundation; with no Invariant Sections, with no Front-Cover Texts,
and with no Back-Cover Texts.
#+end_quote

* Overview
:properties:
:custom_id: h:f0f3dbcb-602d-40cf-b918-8f929c441baf
:end:

The Modus themes are designed for accessible readability.  They conform
with the highest standard for color contrast between any given
combination of background and foreground values.  This corresponds to
the WCAG AAA standard, which specifies a minimum rate of distance in
relative luminance of 7:1.

Modus Operandi (~modus-operandi~) is a light theme, while Modus Vivendi
(~modus-vivendi~) is dark.  Each theme's color palette is designed to meet
the needs of the numerous interfaces that are possible in the Emacs
computing environment.

The overarching objective of this project is to always offer accessible
color combinations.  There shall never be a compromise on this
principle.  If there arises an inescapable trade-off between readability
and stylistic considerations, we will always opt for the former.

To ensure that users have a consistently accessible experience, the
themes strive to achieve as close to full face coverage as possible
([[#h:a9c8f29d-7f72-4b54-b74b-ddefe15d6a19][Face coverage]]).

Starting with version 0.12.0 and onwards, the themes are built into GNU
Emacs.

** How do the themes look like
:properties:
:custom_id: h:69b92089-069c-4ba1-9d94-cc3415fc4f87
:end:
#+cindex: Screenshots

Check the web page with [[https://protesilaos.com/modus-themes-pictures/][the screen shots]].  There are lots of scenarios
on display that draw attention to details and important aspects in the
design of the themes.  They also showcase the numerous customization
options.

[[#h:bf1c82f2-46c7-4eb2-ad00-dd11fdd8b53f][Customization options]].

** Learn about the latest changes
:properties:
:custom_id: h:2cc37c36-6c1a-48b2-a010-1050b270ee18
:end:
#+cindex: Changelog

Please refer to the [[https://protesilaos.com/modus-themes-changelog][web page with the change log]].  It is comprehensive
and covers everything that goes into every tagged release of the themes.

* Installation
:properties:
:custom_id: h:1af85373-7f81-4c35-af25-afcef490c111
:end:

The Modus themes are distributed with Emacs starting with version 28.1.
On older versions of Emacs, they can be installed using Emacs' package
manager or manually from their code repository.  There also exist
packages for distributions of GNU/Linux.

** Install manually from source
:properties:
:custom_id: h:da3414b7-1426-46b8-8e76-47b845b76fd0
:end:

In the following example, we are assuming that your Emacs files are
stored in =~/.emacs.d= and that you want to place the Modus themes in
=~/.emacs.d/modus-themes=.

1. Get the source and store it in the desired path by running the
   following in the command line shell:

: $ git clone https://gitlab.com/protesilaos/modus-themes.git ~/.emacs.d/modus-themes

2. Add that path to your known Elisp libraries' list, by placing this
   snippet of Emacs Lisp in your init file (e.g. {{{file(init.el)}}}):

#+begin_src emacs-lisp
(add-to-list 'load-path "~/.emacs.d/modus-themes")
#+end_src

The themes are now ready to be used: [[#h:3f3c3728-1b34-437d-9d0c-b110f5b161a9][Enable and load]].

** Install from the archives
:properties:
:custom_id: h:c4b10085-149f-43e2-bd4d-347f33aee054
:end:

The =modus-themes= package is available from the GNU ELPA archive, which
is configured by default.

Prior to querying any package archive, make sure to have updated the
index, with {{{kbd(M-x package-refresh-contents)}}}.  Then all you need to do
is type {{{kbd(M-x package-install)}}} and specify the ~modus-themes~.

Note that older versions of the themes used to be distributed as
standalone packages.  This practice has been discontinued starting with
version 1.0.0 of this project.

Once installed, the themes are ready to be used: [[#h:3f3c3728-1b34-437d-9d0c-b110f5b161a9][Enable and load]].

** Install on GNU/Linux
:properties:
:custom_id: h:da640eb1-95dd-4e86-bb4e-1027b27885f0
:end:

The themes are also available from the archives of some distributions of
GNU/Linux.  These should correspond to a tagged release rather than
building directly from the latest Git commit.  It all depends on the
distro's packaging policies.

*** Debian 11 Bullseye
:properties:
:custom_id: h:7e570360-9ee6-4bc5-8c04-9dc11418a3e4
:end:

The themes are part of Debian 11 Bullseye.  Get them with:

#+begin_src sh
sudo apt install elpa-modus-themes
#+end_src

They are now ready to be used: [[#h:3f3c3728-1b34-437d-9d0c-b110f5b161a9][Enable and load]].

*** GNU Guix
:properties:
:custom_id: h:a4ca52cd-869f-46a5-9e16-4d9665f5b88e
:end:

Users of Guix can get the themes with this command:

#+begin_src sh
guix package -i emacs-modus-themes
#+end_src

They are now ready to be used: [[#h:3f3c3728-1b34-437d-9d0c-b110f5b161a9][Enable and load]].

* Enable and load
:properties:
:custom_id: h:3f3c3728-1b34-437d-9d0c-b110f5b161a9
:end:
#+findex: modus-themes-load-themes
#+findex: modus-themes-toggle
#+findex: modus-themes-load-operandi
#+findex: modus-themes-load-vivendi
#+cindex: Essential configuration
#+vindex: modus-themes-after-load-theme-hook

Users of the built-in themes can load and automatically enable the theme
of their preference by adding either form to their init file:

#+begin_src emacs-lisp
(load-theme 'modus-operandi)            ; Light theme
(load-theme 'modus-vivendi)             ; Dark theme
#+end_src

This is all one needs.

Users of packaged variants of the themes must add a few more lines to
ensure that everything works as intended.  First, one has to require the
main library before loading either theme:

#+begin_src emacs-lisp
(require 'modus-themes)
#+end_src

Then it is recommended to load the individual theme files with the
helper function ~modus-themes-load-themes~:

#+begin_src emacs-lisp
;; Load the theme files before enabling a theme (else you get an error).
(modus-themes-load-themes)
#+end_src

Once the libraries that define the themes are enabled, one can activate
a theme with either of the following expressions:

#+begin_src emacs-lisp
(modus-themes-load-operandi)            ; Light theme
;; OR
(modus-themes-load-vivendi)             ; Dark theme
#+end_src

Changes to the available customization options must always be evaluated
before loading a theme ([[#h:bf1c82f2-46c7-4eb2-ad00-dd11fdd8b53f][Customization Options]]).  This is how a basic
setup could look like:

#+begin_src emacs-lisp
(require 'modus-themes)

;; Your customisations here.  For example:
(setq modus-themes-bold-constructs t
      modus-themes-mode-line '3d)

;; Load the theme files before enabling a theme (else you get an error).
(modus-themes-load-themes)

;; Enable the theme of your preference:
(modus-themes-load-operandi)

;; Optionally add a key binding for the toggle between the themes:
(define-key global-map (kbd "<f5>") #'modus-themes-toggle)
#+end_src

[[#h:e979734c-a9e1-4373-9365-0f2cd36107b8][Sample configuration for use-package]].

With those granted, bear in mind a couple of technical points on
~modus-themes-load-operandi~ and ~modus-themes-load-vivendi~, as well as
~modus-themes-toggle~ which relies on them:

1. Those functions call ~load-theme~.  Some users prefer to opt for
   ~enable-theme~ instead ([[#h:e68560b3-7fb0-42bc-a151-e015948f8a35][Differences between loading and enabling]]).

2. The functions will run the ~modus-themes-after-load-theme-hook~ as
   their final step.  This can be employed for bespoke configurations
   ([[#h:f4651d55-8c07-46aa-b52b-bed1e53463bb][Advanced customization (do-it-yourself)]]).  Experienced users may not
   wish to rely on such a hook and the functions that run it: they may
   prefer a custom solution ([[#h:86f6906b-f090-46cc-9816-1fe8aeb38776][A theme-agnostic hook for theme loading]]).

** Sample configuration for use-package
:properties:
:custom_id: h:e979734c-a9e1-4373-9365-0f2cd36107b8
:end:
#+cindex: use-package configuration

It is common for Emacs users to rely on ~use-package~ for declaring
package configurations in their setup.  We use this as an example:

#+begin_src emacs-lisp
(use-package modus-themes
  :ensure                         ; omit this to use the built-in themes
  :init
  ;; Add all your customizations prior to loading the themes
  (setq modus-themes-slanted-constructs t
        modus-themes-bold-constructs nil)

  ;; Load the theme files before enabling a theme (else you get an error).
  (modus-themes-load-themes)
  :config
  ;; Load the theme of your choice:
  (modus-themes-load-operandi) ;; OR (modus-themes-load-vivendi)
  :bind ("<f5>" . modus-themes-toggle))
#+end_src

[[#h:e68560b3-7fb0-42bc-a151-e015948f8a35][Differences between loading and enabling]].

Note: make sure not to customize the variable ~custom-theme-load-path~
or ~custom-theme-directory~ after the themes' package declaration.  That
will lead to failures in loading the files.  If either or both of those
variables need to be changed, their values should be defined before the
package declaration of the themes.

** Differences between loading and enabling
:properties:
:custom_id: h:e68560b3-7fb0-42bc-a151-e015948f8a35
:end:
#+cindex: load-theme VS enable-theme

The reason we recommend ~load-theme~ instead of the other option of
~enable-theme~ is that the former does a kind of "reset" on the face
specs.  It quite literally loads (or re-loads) the theme.  Whereas the
latter simply puts an already loaded theme at the top of the list of
enabled items, re-using whatever state was last loaded.

As such, ~load-theme~ reads all customizations that may happen during
any given Emacs session: even after the initial setup of a theme.
Examples are calls to ~custom-set-faces~, as well as new values assigned
to the options the Modus themes provide ([[#h:bf1c82f2-46c7-4eb2-ad00-dd11fdd8b53f][Customization Options]]).

Our tests show that ~enable-theme~ does not read such variables anew, so
it might appear to the unsuspecting user that the themes are somehow
broken whenever they try to assign a new value to a customization option
or some face.

This "reset" that ~load-theme~ conducts does, however, come at the cost
of being somewhat slower than ~enable-theme~.  Users who have a stable
setup and who seldom update their variables during a given Emacs
session, are better off using something like this:

#+begin_src emacs-lisp
(require 'modus-themes)
(load-theme 'modus-operandi t t)
(load-theme 'modus-vivendi t t)

(enable-theme 'modus-operandi) ;; OR (enable-theme 'modus-vivendi)
#+end_src

[[#h:e979734c-a9e1-4373-9365-0f2cd36107b8][Sample configuration for use-package]].

With the above granted, other sections of the manual discuss how to
configure custom faces, where ~load-theme~ is expected, though
~enable-theme~ could still apply in stable setups:

[[#h:1487c631-f4fe-490d-8d58-d72ffa3bd474][Case-by-case face specs using the themes' palette]].

[[#h:51ba3547-b8c8-40d6-ba5a-4586477fd4ae][Face specs at scale using the themes' palette]].

* Customization Options
:properties:
:custom_id: h:bf1c82f2-46c7-4eb2-ad00-dd11fdd8b53f
:end:

The Modus themes are highly configurable, though they should work well
without any further tweaks.  By default, all customization options are
set to nil.

Remember that all customization options must be evaluated before loading
a theme ([[#h:3f3c3728-1b34-437d-9d0c-b110f5b161a9][Enable and load]]).

** Option for more bold constructs
:properties:
:alt_title: Bold constructs
:description: Toggle bold constructs in code
:custom_id: h:b25714f6-0fbe-41f6-89b5-6912d304091e
:end:
#+vindex: modus-themes-bold-constructs

Symbol: ~modus-themes-bold-constructs~

Possible values:

1. =nil= (default)
2. =t=

The default is to use a bold typographic weight only when it is
required.

With a non-nil value (=t=) display several syntactic constructs in bold
weight.  This concerns keywords and other important aspects of code
syntax.  It also affects certain mode line indicators and command-line
prompts.

** Option for more slanted constructs
:properties:
:alt_title: Slanted constructs
:description: Toggle slanted constructs (italics) in code
:custom_id: h:977c900d-0d6d-4dbb-82d9-c2aae69543d6
:end:
#+vindex: modus-themes-slanted-constructs

Symbol: ~modus-themes-slanted-constructs~

Possible values:

1. =nil= (default)
2. =t=

The default is to not use slanted text (italics) unless it is absolutely
necessary.

With a non-nil value (=t=) choose to render more faces in slanted text.
This typically affects documentation strings and code comments.

** Option for syntax highlighting
:properties:
:alt_title: Syntax styles
:description: Choose the overall aesthetic of code syntax
:custom_id: h:c119d7b2-fcd4-4e44-890e-5e25733d5e52
:end:
#+vindex: modus-themes-syntax

Symbol: ~modus-themes-syntax~

Possible values:

1. =nil= (default)
2. ~faint~
3. ~yellow-comments~
4. ~green-strings~
5. ~yellow-comments-green-strings~
6. ~alt-syntax~
7. ~alt-syntax-yellow-comments~
8. ~faint-yellow-comments~

The default style (nil) for code syntax highlighting is a balanced
combination of colors on the cyan-blue-magenta side of the spectrum.
There is little to no use of greens, yellows, or reds, except when it is
necessary.

Option ~faint~ is like the default in terms of the choice of palette but
applies desaturated color values.

Option ~yellow-comments~ adds a yellow tint to comments.  The rest of the
syntax is the same as the default.

Option ~green-strings~ replaces the blue/cyan/cold color variants in
strings with greener alternatives.  The rest of the syntax remains the
same.

Option ~yellow-comments-green-strings~ combines yellow comments with green
strings and the rest of the default syntax highlighting style.

Option ~alt-syntax~ expands the active spectrum by applying color
combinations with more contrasting hues between them.  Expect to find
red and green variants in addition to cyan, blue, magenta.

Option ~alt-syntax-yellow-comments~ combines ~alt-syntax~ with
~yellow-comments~.

Option ~faint-yellow-comments~ combines the ~faint~ style with
~yellow-comments~.

** Option for no font mixing
:properties:
:alt_title: No mixed fonts
:description: Toggle mixing of font families
:custom_id: h:115e6c23-ee35-4a16-8cef-e2fcbb08e28b
:end:
#+vindex: modus-themes-no-mixed-fonts

Symbol: ~modus-themes-no-mixed-fonts~

Possible values:

1. =nil= (default)
2. =t=

By default, the themes configure some spacing-sensitive faces like Org
tables and code blocks to always inherit from the ~fixed-pitch~ face.
This is to ensure that those constructs remain monospaced even when
users opt for a mode that remaps typeface families, such as the built-in
{{{kbd(M-x variable-pitch-mode)}}}.  Otherwise the layout would appear
broken, due to how spacing is done.  To disable this behaviour, set the
option to =t=.

Users may prefer to use another package for handling mixed typeface
configurations, rather than letting the theme do it, perhaps because a
purpose-specific package has extra functionality.  Two possible options
are ~org-variable-pitch~ and ~mixed-pitch~.

[[#h:defcf4fc-8fa8-4c29-b12e-7119582cc929][Font configurations for Org (and others)]].

** Option for links
:properties:
:alt_title: Link styles
:description: Choose among several styles, with or without underline
:custom_id: h:c119d7b2-fcd4-4e44-890e-5e25733d5e52
:end:
#+vindex: modus-themes-links

Symbol: ~modus-themes-links~

Possible values:

1. =nil= (default)
2. ~faint~
3. ~neutral-underline~
4. ~faint-neutral-underline~
5. ~no-underline~
6. ~underline-only~
7. ~neutral-underline-only~

The default style (nil) for links is to apply an underline and a
saturated color to the affected text.  The color of the two is the same,
which makes the link fairly prominent.

Option ~faint~ follows the same approach as the default, but uses less
intense colors.

Option ~neutral-underline~ changes the underline's color to a subtle gray,
while retaining the default text color.

Option ~faint-neutral-underline~ combines a desaturated text color with a
subtle gray underline.

Option ~no-underline~ removes link underlines altogether, while retaining
their original fairly vivid color.

Option ~underline-only~ applies a prominent underline while making the
affected text colorless (it uses the same foreground as the theme's
default).

Option ~neutral-underline-only~ makes the text colorless while using a
subtle gray underline below it.

NOTE: The placement of the underline, i.e. its proximity to the affected
text, is controlled by the built-in ~x-underline-at-descent-line~,
~x-use-underline-position-properties~, ~underline-minimum-offset~.  Please
refer to their documentation strings.

** Option for command prompt styles
:properties:
:alt_title: Command prompts
:description: Choose among plain, subtle, or intense prompts
:custom_id: h:db5a9a7c-2928-4a28-b0f0-6f2b9bd52ba1
:end:
#+vindex: modus-themes-prompts

Symbol: ~modus-themes-prompts~

Possible values:

1. =nil= (default)
2. ~subtle-accented~ (~subtle~ exists for backward compatibility)
3. ~intense-accented~ (~intense~ exists for backward compatibility)
4. ~subtle-gray~
5. ~intense-gray~

The default does not use any background for minibuffer and command line
prompts.  It relies exclusively on an accented foreground color.

Options ~subtle-accented~ and ~intense-accented~ will change both the
background and the foreground values to use accented color combinations
that follow the hue of the default styles' foreground (e.g. the default
minibuffer prompt is cyan text, so these combinations will involved a
cyan background and an appropriate cyan foreground).  The difference
between the two is that the latter has a more pronounced/noticeable
effect than the former.

Options ~subtle-gray~, ~intense-gray~ are like their accented counterparts,
except they use grayscale values.

** Option for mode line presentation
:properties:
:alt_title: Mode line
:description: Choose among several styles, with or without borders
:custom_id: h:27943af6-d950-42d0-bc23-106e43f50a24
:end:
#+vindex: modus-themes-mode-line

Symbol: ~modus-themes-mode-line~

Possible values:

1. =nil= (default)
2. ~3d~
3. ~moody~
4. ~borderless~
5. ~borderless-3d~
6. ~borderless-moody~

The default produces a two-dimensional effect both for the active and
inactive modelines.  The differences between the two are limited to
distinct shades of grayscale values, with the active being more intense
than the inactive.

Option ~3d~ will make the active modeline look like a three-dimensional
rectangle.  Inactive modelines remain 2D, though they are slightly toned
down relative to the default.  This aesthetic is virtually the same as
what you get when you run Emacs without any customizations (=emacs -Q= on
the command line).

While ~moody~ removes all box effects from the modelines and applies
underline and overline properties instead.  It also tones down a bit the
inactive modelines.  This is meant to optimize things for use with the
[[https://github.com/tarsius/moody][moody package]] (hereinafter referred to as "Moody"), though it can work
fine even without it.

The ~borderless~ option uses the same colors as the default (nil value),
but removes the border effect.  This is done by making the box property
use the same color as the background, effectively blending the two and
creating some padding.

The ~borderless-3d~ and ~borderless-moody~ approximate the ~3d~ and ~moody~
options respectively, while removing the borders.  However, to ensure
that the inactive modelines remain visible, they apply a slightly more
prominent background to them than what their counterparts do (same
inactive background as with the default).

Note that Moody does not expose any faces that the themes could style
directly.  Instead it re-purposes existing ones to render its tabs and
ribbons.  As such, there may be cases where the contrast ratio falls
below the 7:1 target that the themes conform with (WCAG AAA).  To hedge
against this, we configure a fallback foreground for the ~moody~ option,
which will come into effect when the background of the modeline changes
to something less accessible, such as Moody ribbons (read the doc string
of ~set-face-attribute~, specifically ~:distant-foreground~).  This fallback
is activated when Emacs determines that the background and foreground of
the given construct are too close to each other in terms of color
distance.  In effect, users would need to experiment with the variable
~face-near-same-color-threshold~ to trigger the effect.  We find that a
value of =45000= will suffice, contrary to the default =30000=.  Do not set
the value too high, because that would have the adverse effect of always
overriding the default color (which has been carefully designed to be
highly accessible).

Furthermore, because Moody expects an underline and overline instead of
a box style, it is advised you include this in your setup:

#+begin_src emacs-lisp
(setq x-underline-at-descent-line t)
#+end_src

** Option for completion framework aesthetics
:properties:
:alt_title: Completion UIs
:description: Choose among standard, moderate, or opinionated looks
:custom_id: h:f1c20c02-7b34-4c35-9c65-99170efb2882
:end:
#+vindex: modus-themes-completions

Symbol: ~modus-themes-completions~

Possible values:

1. =nil= (default)
2. ~moderate~
3. ~opinionated~

This is a special option that has different effects depending on the
completion UI.  The interfaces can be grouped in two categories, based
on their default aesthetics: (i) those that only or mostly use
foreground colors for their interaction model, and (ii) those that
combine background and foreground values for some of their metaphors.
The former category encompasses Icomplete, Ido, Selectrum as well as
pattern matching styles like Orderless and Flx.  The latter covers Helm,
Ivy, and similar.

A value of =nil= will respect the metaphors of each completion framework.

Option ~moderate~ applies a combination of background and foreground that
is fairly subtle.  For Icomplete and friends this constitutes a
departure from their default aesthetics, however the difference is
small.  While Helm, Ivy et al appear slightly different than their
original looks, as they are toned down a bit.

Option ~opinionated~ uses color combinations that refashion the completion
UI.  For the Icomplete camp this means that intense background and
foreground combinations are used: in effect their looks emulate those of
Helm, Ivy and co. in their original style.  Whereas the other group of
packages will revert to an even more nuanced aesthetic with some
additional changes to the choice of hues.

To appreciate the scope of this customization option, you should spend
some time with every one of the =nil= (default), ~moderate~, and ~opinionated~
possibilities.

** Option for fringe visibility
:properties:
:alt_title: Fringes
:description: Choose among invisible, subtle, or intense fringe styles
:custom_id: h:1983c3fc-74f6-44f3-b917-967c403bebae
:end:
#+vindex: modus-themes-fringes

Symbol: ~modus-themes-fringes~

Possible values:

1. =nil= (default)
2. ~subtle~
3. ~intense~

The default is to use the same color as that of the main background,
meaning that the fringes are not obvious though they still occupy the
space given to them by ~fringe-mode~.

Options ~subtle~ and ~intense~ apply a gray background, making the fringes
visible.  The difference between the two is one of degree, as their
names imply.

** Option for language checkers
:properties:
:alt_title: Language checkers
:description: Control the style of language checkers/linters
:custom_id: h:4b13743a-8ebf-4d2c-a043-cceba10b1eb4
:end:
#+vindex: modus-themes-lang-checkers

Symbol: ~modus-themes-lang-checkers~

Possible values:

1. =nil= (default)
2. ~subtle-foreground~
3. ~intense-foreground~
4. ~straight-underline~
5. ~subtle-foreground-straight-underline~
6. ~intense-foreground-straight-underline~
7. ~colored-background~

Nil (the default) applies a color-coded underline to the affected text,
while it leaves the original foreground in tact.  If the display spec
where Emacs runs in has support for it (e.g. Emacs GUI), the underline's
style is that of a wave, otherwise it is a straight line.

Options ~subtle-foreground~ and ~intense-foreground~ follow the same
color-coding pattern and wavy underline of the default, while extending
it with a corresponding foreground value for the affected text.  The
difference between the two options is one of degree, as their names
suggest.

Option ~straight-underline~ is like the default but always applies a
straight line under the affected text.  Same principle for
~subtle-foreground-straight-underline~ and its counterpart
~intense-foreground-straight-underline~.

Option ~colored-background~ uses a straight underline, a tinted
background, and a suitable foreground.  All are color-coded.  This is
the most intense combination of face properties.

The present variable affects packages and/or face groups such as those
of =flyspell=, =flymake=, =flycheck=, ~artbollocks-mode~, and ~writegood-mode~.

NOTE: The placement of the straight underline, though not the wave
style, is controlled by the built-in ~x-underline-at-descent-line~,
~x-use-underline-position-properties~, ~underline-minimum-offset~.  Please
refer to their documentation strings.

** Option for line highlighting (hl-line-mode)
:properties:
:alt_title: Line highlighting
:description: Toggle intense style for current line highlighting
:custom_id: h:1dba1cfe-d079-4c13-a810-f768e8789177
:end:
#+vindex: modus-themes-intense-hl-line

Symbol: ~modus-themes-intense-hl-line~

Possible values:

1. =nil= (default)
2. =t=

The default is to use a subtle gray background for ~hl-line-mode~ and its
global equivalent.

With a non-nil value (=t=) use a more prominent background color instead.

This affects several packages that enable ~hl-line-mode~, such as =elfeed=
and =mu4e=.

** Option for line numbers (display-line-numbers-mode)
:properties:
:alt_title: Line numbers
:description: Toggle subtle style for line numbers
:custom_id: h:8c4a6230-2e43-4aa2-a631-3b7179392e09
:end:
#+vindex: modus-themes-subtle-line-numbers

Symbol: ~modus-themes-subtle-line-numbers~

Possible value:

1. =nil= (default)
2. =t=

The default style for ~display-line-numbers-mode~ and its global variant
is to apply a subtle gray background to the line numbers.  The current
line has a more pronounced background and foreground combination to
bring more attention to itself.

Similarly, the faces for ~display-line-numbers-major-tick~ and its
counterpart ~display-line-numbers-minor-tick~ use appropriate styles that
involve a bespoke background and foreground combination.

With a non-nil value (=t=), line numbers have no background of their own.
Instead they retain the primary background of the theme, blending with
the rest of the buffer.  Foreground values for all relevant faces are
updated to accommodate this aesthetic.

** Option for parenthesis matching (show-paren-mode)
:properties:
:alt_title: Matching parentheses
:description: Choose between various styles for matching delimiters/parentheses
:custom_id: h:e66a7e4d-a512-4bc7-9f86-fbbb5923bf37
:end:
#+vindex: modus-themes-paren-match

Symbol: ~modus-themes-paren-match~

Possible values:

1. =nil= (default)
2. ~subtle-bold~
3. ~intense~
4. ~intense-bold~

Nil means to use a subtle tinted background color for the matching
delimiters.

Option ~intense~ applies a saturated background color.

Option ~subtle-bold~ is the same as the default, but also makes use of
bold typographic weight (inherits the ~bold~ face).

Option ~intense-bold~ is the same as ~intense~, while it also uses a bold
weight.

This customization variable affects tools such as the built-in
~show-paren-mode~ and the =smartparens= package.

** Option for active region
:properties:
:alt_title: Active region
:description: Choose between various styles for the active region
:custom_id: h:60798063-b4ad-45ea-b9a7-ff7b5c0ab74c
:end:
#+vindex: modus-themes-region

Symbol: ~modus-themes-region~

Possible values:

1. =nil= (default)
2. ~no-extend~
3. ~bg-only~
4. ~bg-only-no-extend~

Nil means to only use a prominent gray background with a neutral
foreground.  The foreground overrides all syntax highlighting.  The
region extends to the edge of the window.

Option ~no-extend~ preserves the default aesthetic but prevents the region
from extending to the edge of the window.

Option ~bg-only~ applies a faint tinted background that is distinct from
all others used in the theme, while it does not override any existing
colors.  It extends to the edge of the window.

Option ~bg-only-no-extend~ is a combination of the ~bg-only~ and ~no-extend~
options.

** Option for diff buffer looks
:properties:
:alt_title: Diffs
:description: Choose among intense, desaturated, or text-only diffs
:custom_id: h:ea7ac54f-5827-49bd-b09f-62424b3b6427
:end:
#+vindex: modus-themes-diffs

Symbol: ~modus-themes-diffs~

Possible values:

1. =nil= (default)
2. ~desaturated~
3. ~fg-only~
4. ~bg-only~
5. ~deuteranopia~

By default the themes apply rich coloration to the output of diffs, such
as those of ~diff-mode~, ~ediff~, ~smerge-mode~, and Magit.  These are
color combinations of an accented background and foreground so that, for
example, added lines have a pronounced green background with an
appropriate shade of green for the affected text.  Word-wise or
"refined" changes follow this pattern but use different shades of those
colors to remain distinct.

Option ~desaturated~ tones down all relevant color values.  It still
combines an accented background with an appropriate foreground, yet its
overall impression is fairly subtle.  Refined changes are a bit more
intense to fulfil their intended function, though still less saturated
than default.

Option ~fg-only~ will remove most accented backgrounds and instead rely
on color-coded text to denote changes.  For instance, added lines use a
green foreground, while their background is the same as the rest of the
buffer.  Word-wise highlights still use a background value which is,
nonetheless, more subtle than its default equivalent.

Option ~bg-only~ applies color-coded backgrounds but does not override
any syntax highlighting that may be present.  This makes it suitable for
use with a non-nil value for ~diff-font-lock-syntax~ (which is the
default for ~diff-mode~ buffers in Emacs 27 or higher).

Option ~deuteranopia~ optimizes for red-green color deficiency.  It
replaces all instances of green with blue variants.  This is to ensure
that indicators for "removed" and "added" states are not mistaken for
each other.

Concerning Magit, an extra set of tweaks are introduced for the effect
of highlighting the current diff hunk, so as to remain aligned with the
overall experience of that mode.  Expect changes that are consistent
with the overall intent of the aforementioned.  Note, however, that the
~bg-only~ option will not deliver the intended results in Magit diffs
because no syntax highlighting is used there (last checked with Magit
version 20201116.1057, though upstream has a plan to eventually support
such a feature---this entry shall be updated accordingly).

** Option for org-mode block styles
:properties:
:alt_title: Org mode blocks
:description: Choose among plain, grayscale, or rainbow styles
:custom_id: h:b7e328c0-3034-4db7-9cdf-d5ba12081ca2
:end:
#+vindex: modus-themes-org-blocks

Symbol: ~modus-themes-org-blocks~

Possible values:

1. =nil= (default)
2. ~grayscale~
3. ~rainbow~

The default is to use the same background as the rest of the buffer for
the contents of the block.

Option ~grayscale~ applies a subtle neutral gray background to the block's
contents.  It will also extend to the edge of the window the background
of the "begin" and "end" block delimiter lines (only relevant for Emacs
versions >= 27 where the 'extend' keyword is part of the face
specifications).

Option ~rainbow~ uses an accented background for the contents of the
block.  The exact color will depend on the programming language and is
controlled by the ~org-src-block-faces~ variable.  This is most suitable
for users who work on literate programming documents that mix and match
several languages.

Note that the "rainbow" blocks may require you to also reload the
major-mode so that the colors are applied consistently throughout: use
{{{kbd(M-x org-mode)}}} or {{{kbd(M-x org-mode-restart)}}} to refresh the buffer.
Or start typing in each code block (inefficient at scale, but it still
works).

** Option for org-habit graph styles
:properties:
:alt_title: Org agenda habits
:description: Choose among standard, simplified, or traffic light styles
:custom_id: h:b7e328c0-3034-4db7-9cdf-d5ba12081ca2
:end:
#+vindex: modus-themes-org-habit

Symbol: ~modus-themes-org-habit~

Possible values:

1. =nil= (default)
2. ~simplified~
3. ~traffic-light~

The default is meant to conform with the original aesthetic of
=org-habit=.  It employs all four color codes that correspond to the
org-habit states---clear, ready, alert, and overdue---while
distinguishing between their present and future variants.  This results
in a total of eight colors in use: red, yellow, green, blue, in tinted
and shaded versions.  They cover the full set of information provided by
the =org-habit= consistency graph.

Option ~simplified~ is like the default except that it removes the
dichotomy between current and future variants by applying uniform
color-coded values.  It applies a total of four colors: red, yellow,
green, blue.  They produce a simplified consistency graph that is more
legible (or less "busy") than the default.  The intent is to shift focus
towards the distinction between the four states of a habit task, rather
than each state's present/future outlook.

Option ~traffic-light~ further reduces the available colors to red,
yellow, and green.  As in ~simplified~, present and future variants appear
uniformly, but differently from it, the 'clear' state is rendered in a
green hue, instead of the original blue.  This is meant to capture the
use-case where a habit task being "too early" is less important than it
being "too late".  The difference between ready and clear states is
attenuated by painting both of them using shades of green.  This option
thus highlights the alert and overdue states.

** Option for the headings' overall style
:properties:
:alt_title: Heading styles
:description: Choose among several styles, also per heading level
:custom_id: h:271eff19-97aa-4090-9415-a6463c2f9ae1
:end:
#+vindex: modus-themes-headings

This is defined as an alist and, therefore, uses a different approach
than other customization options documented in this manual.

Symbol: ~modus-themes-headings~

Possible values, which can be specified for each heading level (examples
further below):

+ nil (default fallback option---covers all heading levels)
+ =t= (default style for a single heading, when the fallback differs)
+ ~no-bold~
+ ~line~
+ ~line-no-bold~
+ ~rainbow~
+ ~rainbow-line~
+ ~rainbow-line-no-bold~
+ ~highlight~
+ ~highlight-no-bold~
+ ~rainbow-highlight~
+ ~rainbow-highlight-no-bold~
+ ~section~
+ ~section-no-bold~
+ ~rainbow-section~
+ ~rainbow-section-no-bold~
+ ~no-color~
+ ~no-color-no-bold~

To control faces per level from 1-8, use something like this:

#+begin_src emacs-lisp
(setq modus-themes-headings
      '((1 . section)
        (2 . section-no-bold)
        (3 . rainbow-line)
        (t . rainbow-line-no-bold)))
#+end_src

The above uses the ~section~ value for heading levels 1, ~section-no-bold~
for headings 2, ~rainbow-line~ for 3.  All other levels fall back to
~rainbow-line-no-bold~.

To set a uniform value for all heading levels, use this pattern:

#+begin_src emacs-lisp
;; A given style for every heading
(setq modus-themes-headings
      '((t . section)))

;; Default aesthetic for every heading
(setq modus-themes-headings
      '())
#+end_src

The default style for headings uses a fairly desaturated foreground
value in combination with bold typographic weight.  To specify this
style for a given level N, assuming you wish to have another fallback
option, just specify the value =t= like this:

#+begin_src emacs-lisp
(setq modus-themes-headings
      '((1 . t)
        (2 . line)
        (t . rainbow-line-no-bold)))
#+end_src

A description of all other possible styles beyond the default:

+ ~no-bold~ retains the default text color while removing the bold
  typographic weight.

+ ~line~ is the same as the default plus an overline across the
  heading's length.

+ ~line-no-bold~ is the same as ~line~ without bold weight.

+ ~rainbow~ uses a more colorful foreground in combination with bold
  typographic weight.

+ ~rainbow-line~ is the same as ~rainbow~ plus an overline.

+ ~rainbow-line-no-bold~ is the same as ~rainbow-line~ without the bold
  weight.

+ ~highlight~ retains the default style of a fairly desaturated
  foreground combined with a bold weight and adds to it a subtle
  accented background.

+ ~highlight-no-bold~ is the same as ~highlight~ without a bold weight.

+ ~rainbow-highlight~ is the same as ~highlight~ but with a more
  colorful foreground.

+ ~rainbow-highlight-no-bold~ is the same as ~rainbow-highlight~ without
  a bold weight.

+ ~section~ retains the default looks and adds to them both an overline
  and a slightly accented background.  It is, in effect, a combination
  of the ~line~ and ~highlight~ values.

+ ~section-no-bold~ is the same as ~section~ without a bold weight.

+ ~rainbow-section~ is the same as ~section~ but with a more colorful
  foreground.

+ ~rainbow-section-no-bold~ is the same as ~rainbow-section~ without a
  bold weight.

+ ~no-color~ does not apply any color to the heading, meaning that it
  uses the foreground of the ~default~ face.  It still renders the text
  with a bold typographic weight.

+ ~no-color-no-bold~ is like ~no-color~ but without the bold weight.

** Option for scaled headings
:properties:
:alt_title: Scaled headings
:description: Toggle scaling of headings
:custom_id: h:075eb022-37a6-41a4-a040-cc189f6bfa1f
:end:
#+vindex: modus-themes-scale-headings

Symbol: ~modus-themes-scale-headings~

Possible values:

1. =nil= (default)
2. =t=

The default is to use the same size for headings and paragraph text.

With a non-nil value (=t=) make headings larger in height relative to the
main text.  This is noticeable in modes like Org, Markdown, and Info.

*** Control the scale of headings
:properties:
:alt_title: Scaled heading sizes
:description: Specify rate of increase for scaled headings
:custom_id: h:6868baa1-beba-45ed-baa5-5fd68322ccb3
:end:

In addition to the toggle for enabling scaled headings, users can also
specify a number of their own.

+ If it is a floating point, say, =1.5=, it is interpreted as a multiple
  of the base font size.  This is the recommended method, because it
  will always adapt to changes in the base font size, such as while
  using the ~text-scale-adjust~ command.

+ If it is an integer, it is read as an absolute font height that is
  1/10 of the typographic point size.  Thus a value of =18pt= must be
  expressed as =180=.  Setting an absolute value is discouraged, as it
  will break the layout in cases where the base font size must change,
  such as with the ~text-scale-adjust~ command ([[#h:defcf4fc-8fa8-4c29-b12e-7119582cc929][Font configurations]]).
  While we discourage using absolute values, we still provide for this
  option for users who do not need to perform text-scaling operations or
  who are content with whatever discrepancies in height.

Below are the variables in their default values, using the floating
point paradigm.  The numbers are very conservative, but one is free to
change them to their liking, such as =1.2=, =1.4=, =1.6=, =1.8=, =2.0=---or use a
resource for finding a consistent scale:

#+begin_src emacs-lisp
(setq modus-themes-scale-1 1.05
      modus-themes-scale-2 1.1
      modus-themes-scale-3 1.15
      modus-themes-scale-4 1.2
      modus-themes-scale-5 1.3)
#+end_src

As for the application of that scale, the variables that range from
~modus-themes-scale-1~ up to ~modus-themes-scale-4~ apply to regular
headings within the context of the given major mode.  The former is the
smallest, while the latter is the largest.  "Regular headings" are those
that have a standard syntax for their scale, such as Org mode's eight
levels of asterisks or Markdown's six columns.

Whereas ~modus-themes-scale-5~ is applied to special headings that do not
conform with the aforementioned syntax, yet which are expected to be
larger than the largest value on that implied scale.  Put concretely,
Org's =#+title= meta datum is not part of the eight levels of headings in
an Org file, yet is supposed to signify the primary header.  Similarly,
the Org Agenda's structure headings are not part of a recognisable scale
and so they also get ~modus-themes-scale-5~.

Users who wish to maintain scaled headings for the normal syntax while
preventing special headings from standing out, can assign a value of =1.0=
to ~modus-themes-scale-5~ to make it the same as body text (or whatever
value would render it indistinguishable from the desired point of
reference).

Note that in earlier versions of Org, scaling would only increase the
size of the heading, but not of keywords that were added to it, like
"TODO".  The issue has been fixed upstream:
<https://protesilaos.com/codelog/2020-09-24-org-headings-adapt/>.

** Option for variable-pitch font in UI elements
:properties:
:alt_title: UI typeface
:description: Toggle the use of variable-pitch across the User Interface
:custom_id: h:16cf666c-5e65-424c-a855-7ea8a4a1fcac
:end:
#+vindex: modus-themes-variable-pitch-ui

Symbol: ~modus-themes-variable-pitch-ui~

Possible values:

1. =nil= (default)
2. =t=

This option concerns User Interface elements that are under the direct
control of Emacs.  In particular: the mode line, header line, tab bar,
and tab line.

The default is to use the same font as the rest of Emacs, which usually
is a monospaced family.

With a non-nil value (=t=) apply a proportionately spaced typeface.  This
is done by assigning the ~variable-pitch~ face to the relevant items.

[[#h:defcf4fc-8fa8-4c29-b12e-7119582cc929][Font configurations for Org and others]].

** Option for variable-pitch font in headings
:properties:
:alt_title: Headings' typeface
:description: Toggle the use of variable-pitch in headings
:custom_id: h:97caca76-fa13-456c-aef1-a2aa165ea274
:end:
#+vindex: modus-themes-variable-pitch-headings

Symbol: ~modus-themes-variable-pitch-headings~

Possible values:

1. =nil= (default)
2. =t=

The default is to use the main font family, which typically is
monospaced.

With a non-nil value (=t=) apply a proportionately spaced typeface, else
"variable-pitch", to headings (such as in Org mode).

[[#h:defcf4fc-8fa8-4c29-b12e-7119582cc929][Font configurations for Org and others]].

* Advanced customization (do-it-yourself)
:properties:
:custom_id: h:f4651d55-8c07-46aa-b52b-bed1e53463bb
:end:

Unlike the predefined customization options which follow a clear pattern
of allowing the user to quickly specify their preference, the themes
also provide a more flexible, albeit difficult, mechanism to control
things with precision ([[#h:bf1c82f2-46c7-4eb2-ad00-dd11fdd8b53f][Customization Options]]).

This section is of interest only to users who are prepared to maintain
their own local tweaks and who are willing to deal with any possible
incompatibilities between versioned releases of the themes.  As such,
they are labelled as "do-it-yourself" or "DIY".

** Per-theme customization settings (DIY)
:properties:
:custom_id: h:a897b302-8e10-4a26-beab-3caaee1e1193
:end:

If you prefer to maintain different customization options between the
two themes, it is best you write your own functions that first set those
options and then load the relevant theme.  The following code does
exactly that by simply differentiating the two themes on the choice of
bold constructs in code syntax (enabled for one, disabled for the
other).

#+begin_src emacs-lisp
(defun my-demo-modus-operandi ()
  (interactive)
  (setq modus-themes-bold-constructs t) ; ENABLE bold
  (modus-themes-load-operandi))

(defun my-demo-modus-vivendi ()
  (interactive)
  (setq modus-themes-bold-constructs nil) ; DISABLE bold
  (modus-themes-load-vivendi))

(defun my-demo-modus-themes-toggle ()
  (if (eq (car custom-enabled-themes) 'modus-operandi)
      (my-demo-modus-vivendi)
    (my-demo-modus-operandi)))
#+end_src

Then assign ~my-demo-modus-themes-toggle~ to a key instead of the
equivalent the themes provide.

For a more elaborate design, it is better to inspect the source code of
~modus-themes-toggle~ and relevant functions.

** Case-by-case face specs using the themes' palette (DIY)
:properties:
:custom_id: h:1487c631-f4fe-490d-8d58-d72ffa3bd474
:end:
#+findex: modus-themes-color
#+findex: modus-themes-color-alts
#+cindex: Extracting individual colors

This section is about tweaking individual faces.  If you plan to do
things at scale, consult the next section: [[#h:51ba3547-b8c8-40d6-ba5a-4586477fd4ae][Set multiple faces]].

We already covered in previous sections how to toggle between the themes
and how to configure options prior to loading.  We also explained that
some of the functions made available to users will fire up a hook that
can be used to pass tweaks in the post-theme-load phase.

Now assume you wish to change a single face, say, the ~cursor~.  And you
would like to get the standard "blue" color value of the active Modus
theme, whether it is Modus Operandi or Modus Vivendi.  To do that, you
can use the ~modus-themes-color~ function.  It accepts a symbol that is
associated with a color in ~modus-themes-operandi-colors~ and
~modus-themes-vivendi-colors~.  Like this:

#+begin_src emacs-lisp
(modus-themes-color 'blue)
#+end_src

The function always extracts the color value of the active Modus theme.

#+begin_src emacs-lisp
(progn
  (load-theme 'modus-operandi t)
  (modus-themes-color 'blue))           ; "#0031a9" for `modus-operandi'

(progn
  (load-theme 'modus-vivendi t)
  (modus-themes-color 'blue))           ; "#2fafff" for `modus-vivendi'
#+end_src

Do {{{kbd(C-h v)}}} on the aforementioned variables to check all the available
symbols that can be passed to this function.

With that granted, let us expand the example to actually change the
~cursor~ face's background property.  We employ the built-in function of
~set-face-attribute~:

#+begin_src emacs-lisp
(set-face-attribute 'cursor nil :background (modus-themes-color 'blue))
#+end_src

If you evaluate this form, your cursor will become blue.  But if you
change themes, such as with ~modus-themes-toggle~, your edits will be
lost, because the newly loaded theme will override the =:background=
attribute you had assigned to that face.

For such changes to persist, we need to make them after loading the
theme.  So we rely on ~modus-themes-after-load-theme-hook~, which gets
called from ~modus-themes-load-operandi~, ~modus-themes-load-vivendi~, as
well as the command ~modus-themes-toggle~.  Here is a sample function that
tweaks two faces and then gets added to the hook:

#+begin_src emacs-lisp
(defun my-modus-themes-custom-faces ()
  (set-face-attribute 'cursor nil :background (modus-themes-color 'blue))
  (set-face-attribute 'font-lock-type-face nil :foreground (modus-themes-color 'magenta-alt)))

(add-hook 'modus-themes-after-load-theme-hook #'my-modus-themes-custom-faces)
#+end_src

[[#h:86f6906b-f090-46cc-9816-1fe8aeb38776][A theme-agnostic hook for theme loading]].

Using this principle, it is possible to override the styles of faces
without having to find color values for each case.

Another application is to control the precise weight for bold
constructs.  This is particularly useful if your typeface has several
variants such as "heavy", "extrabold", "semibold".  All you have to do
is edit the ~bold~ face.  For example:

#+begin_src emacs-lisp
(set-face-attribute 'bold nil :weight 'semibold)
#+end_src

Remember to use the custom function and hook combo we demonstrated
above.  Because the themes do not hard-wire a specific weight, this
simple form is enough to change the weight of all bold constructs
throughout the interface.

Finally, there are cases where you want to tweak colors though wish to
apply different ones to each theme, say, a blue hue for Modus Operandi
and a shade of red for Modus Vivendi.  To this end, we provide
~modus-themes-color-alts~ as a convenience function to save you from the
trouble of writing separate wrappers for each theme.  It still returns a
single value by querying either of ~modus-themes-operandi-colors~ and
~modus-themes-vivendi-colors~, only here you pass the two keys you want,
first for ~modus-operandi~ then ~modus-vivendi~.

Take the previous example with the ~cursor~ face:

#+begin_src emacs-lisp
;; Blue for `modus-operandi' and red for `modus-vivendi'
(set-face-attribute 'cursor nil :background (modus-themes-color-alts 'blue 'red))
#+end_src

** Face specs at scale using the themes' palette (DIY)
:properties:
:custom_id: h:51ba3547-b8c8-40d6-ba5a-4586477fd4ae
:end:
#+findex: modus-themes-with-colors
#+cindex: Extracting colors en masse

The examples here are for large scale operations.  For simple, one-off
tweaks, you may prefer the approach documented in the previous section
([[#h:1487c631-f4fe-490d-8d58-d72ffa3bd474][Case-by-case face specs using the themes' palette]]).

The ~modus-themes-with-colors~ macro lets you retrieve multiple color
values by employing the backquote/backtick and comma notation.  The
values are stored in the alists ~modus-themes-operandi-colors~ and
~modus-themes-vivendi-colors~, while the macro always queries that of the
active Modus theme.

Here is an abstract example that just returns a list of color values
while ~modus-operandi~ is enabled:

#+begin_src emacs-lisp
(modus-themes-with-colors
  (list fg-main
        blue-faint
        magenta
        magenta-alt-other
        cyan-alt-other
        fg-special-cold
        blue-alt
        magenta-faint
        cyan
        fg-main
        green-faint
        red-alt-faint
        blue-alt-faint
        fg-special-warm
        cyan-alt
        blue))
;; =>
;; ("#000000" "#002f88" "#721045" "#5317ac"
;;  "#005a5f" "#093060" "#2544bb" "#752f50"
;;  "#00538b" "#000000" "#104410" "#702f00"
;;  "#003f78" "#5d3026" "#30517f" "#0031a9")
#+end_src

Getting a list of colors may have its applications, though what you are
most likely interested in is how to use those variables to configure
several faces at once.  To do so we can rely on the built-in
~custom-set-faces~ function, which sets face specifications for the
special =user= theme.  That "theme" gets applied on top of regular themes
like ~modus-operandi~ and ~modus-vivendi~.

This is how it works:

#+begin_src emacs-lisp
(modus-themes-with-colors
  (custom-set-faces
   `(cursor ((,class :background ,blue)))
   `(mode-line ((,class :background ,yellow-nuanced-bg
                        :foreground ,yellow-nuanced-fg)))
   `(mode-line-inactive ((,class :background ,blue-nuanced-bg
                                 :foreground ,blue-nuanced-fg)))))
#+end_src

The above snippet will immediately refashion the faces it names once it
is evaluated.  However, if you switch between the Modus themes, say,
from ~modus-operandi~ to ~modus-vivendi~, the colors will not get updated to
match those of the new theme.  To make things work across the themes, we
need to employ the same technique we discussed in the previous section,
namely, to pass our changes at the post-theme-load phase via a hook.

The themes provide the ~modus-themes-after-load-theme-hook~, which gets
called from ~modus-themes-load-operandi~, ~modus-themes-load-vivendi~, as
well as the command ~modus-themes-toggle~.  With this knowledge, you can
wrap the macro in a function and then assign that function to the hook.
Thus:

#+begin_src emacs-lisp
(defun my-modus-themes-custom-faces ()
  (modus-themes-with-colors
    (custom-set-faces
     `(cursor ((,class :background ,blue)))
     `(mode-line ((,class :background ,yellow-nuanced-bg
                          :foreground ,yellow-nuanced-fg)))
     `(mode-line-inactive ((,class :background ,blue-nuanced-bg
                                   :foreground ,blue-nuanced-fg))))))

(add-hook 'modus-themes-after-load-theme-hook #'my-modus-themes-custom-faces)
#+end_src

[[#h:86f6906b-f090-46cc-9816-1fe8aeb38776][A theme-agnostic hook for theme loading]].

To discover the faces defined by all loaded libraries, you may do
{{{kbd(M-x list-faces-display)}}}.  Be warned that when you =:inherit= a face
you are introducing an implicit dependency, so try to avoid doing so for
libraries other than the built-in {{{file(faces.el)}}} (or at least understand
that things may break if you inherit from a yet-to-be-loaded face).

Also bear in mind that these examples are meant to work with the Modus
themes.  If you are cycling between multiple themes you may encounter
unforeseen issues, such as the colors of the Modus themes being applied
to a non-Modus item.

Finally, note that you can still use other functions where those make
sense.  For example, the ~modus-themes-color-alts~ that was discussed in
the previous section.  Adapt the above example like this:

#+begin_src emacs-lisp
...
(modus-themes-with-colors
  (custom-set-faces
   `(cursor ((,class :background ,(modus-themes-color-alts 'blue 'green))))
   ...))
#+end_src

** Override colors (DIY)
:properties:
:custom_id: h:307d95dd-8dbd-4ece-a543-10ae86f155a6
:end:
#+vindex: modus-themes-operandi-color-overrides
#+vindex: modus-themes-vivendi-color-overrides
#+cindex: Change a theme's colors

The themes provide a mechanism for overriding their color values.  This
is controlled by the variables ~modus-themes-operandi-color-overrides~ and
~modus-themes-vivendi-color-overrides~, which are alists that should
mirror a subset of the associations in ~modus-themes-operandi-colors~ and
~modus-themes-vivendi-colors~ respectively.  As with all customisations,
overriding must be done before loading the affected theme.

Let us approach the present topic one step at a time.  Here is a
simplified excerpt of the default palette for Modus Operandi with some
basic background values that apply to buffers and the mode line
(remember to inspect the actual value to find out all the associations
that can be overridden):

#+begin_src emacs-lisp
(defconst modus-themes-colors-operandi
  '((bg-main . "#ffffff")
    (bg-dim . "#f8f8f8")
    (bg-alt . "#f0f0f0")
    (bg-active . "#d7d7d7")
    (bg-inactive . "#efefef")))
#+end_src

As one can tell, we bind a key to a hexadecimal RGB color value.  Now
say we wish to override those specific values and have our changes
propagate to all faces that use those keys.  We could write something
like this, which adds a subtle ochre tint:

#+begin_src emacs-lisp
(setq modus-themes-operandi-color-overrides
      '((bg-main . "#fefcf4")
        (bg-dim . "#faf6ef")
        (bg-alt . "#f7efe5")
        (bg-active . "#e8dfd1")
        (bg-inactive . "#f6ece5")))
#+end_src

Once this is evaluated, any subsequent loading of ~modus-operandi~ will
use those values instead of the defaults.  No further intervention is
required.

To reset the changes, we apply this and reload the theme:

#+begin_src emacs-lisp
(setq modus-themes-operandi-color-overrides nil)
#+end_src

Users who wish to leverage such a mechanism can opt to implement it
on-demand by means of a global minor mode.  The following snippet covers
both themes and expands to some more assosiations in the palette:

#+begin_src emacs-lisp
(define-minor-mode my-modus-themes-tinted
  "Tweak some Modus themes colors."
  :init-value nil
  :global t
  (if my-modus-themes-tinted
      (setq modus-themes-operandi-color-overrides
            '((bg-main . "#fefcf4")
              (bg-dim . "#faf6ef")
              (bg-alt . "#f7efe5")
              (bg-hl-line . "#f4f0e3")
              (bg-active . "#e8dfd1")
              (bg-inactive . "#f6ece5")
              (bg-region . "#c6bab1")
              (bg-header . "#ede3e0")
              (bg-tab-bar . "#dcd3d3")
              (bg-tab-active . "#fdf6eb")
              (bg-tab-inactive . "#c8bab8")
              (fg-unfocused . "#55556f"))
            modus-themes-vivendi-color-overrides
            '((bg-main . "#100b17")
              (bg-dim . "#161129")
              (bg-alt . "#181732")
              (bg-hl-line . "#191628")
              (bg-active . "#282e46")
              (bg-inactive . "#1a1e39")
              (bg-region . "#393a53")
              (bg-header . "#202037")
              (bg-tab-bar . "#262b41")
              (bg-tab-active . "#120f18")
              (bg-tab-inactive . "#3a3a5a")
              (fg-unfocused . "#9a9aab")))
    (setq modus-themes-operandi-color-overrides nil
          modus-themes-vivendi-color-overrides nil)))
#+end_src

With this in place, one can invoke {{{kbd(M-x my-modus-themes-tinted)}}} and
then load the Modus theme of their choice.  The new palette subset will
come into effect: subtle ochre tints for Modus Operandi and night sky
shades for Modus Vivendi.  Switching between the two themes, such as
with {{{kbd(M-x modus-themes-toggle)}}} will also use the overrides.

Given that this is a user-level customisation, one is free to implement
whatever color values they desire, even if the possible combinations
fall below the minimum 7:1 contrast ratio that governs the design of the
themes (the WCAG AAA legibility standard).  Preferences aside, it is
advised to inspect the source code of ~modus-themes-operandi-colors~ and
~modus-themes-vivendi-colors~ to read the inline commentary: it explains
what the intended use of each palette subset is.

Furthermore, users may benefit from the ~modus-themes-contrast~ function
that we provide: [[#h:02e25930-e71a-493d-828a-8907fc80f874][test color combinations]].  It measures the contrast
ratio between two color values, so it can help in overriding the palette
(or a subset thereof) without making the end result inaccessible.

** Font configurations for Org and others (DIY)
:properties:
:custom_id: h:defcf4fc-8fa8-4c29-b12e-7119582cc929
:end:
#+cindex: Font configurations

The themes are designed to cope well with mixed font configurations.

[[#h:115e6c23-ee35-4a16-8cef-e2fcbb08e28b][Option for no font mixing]].

This mostly concerns ~org-mode~ and ~markdown-mode~, though expect to find
it elsewhere like in ~Info-mode~.

In practice it means that the user can safely opt for a more
prose-friendly proportionately spaced typeface as their default, while
letting spacing-sensitive elements like tables and inline code always
use a monospaced font, by inheriting from the ~fixed-pitch~ face.

Users can try the built-in {{{kbd(M-x variable-pitch-mode)}}} to see the
effect in action.

To make everything use your desired font families, you need to configure
the ~variable-pitch~ (proportional spacing) and ~fixed-pitch~ (monospaced)
faces respectively.  It may also be convenient to set your main typeface
by configuring the ~default~ face the same way.

Put something like this in your initialization file (also consider
reading the doc string of ~set-face-attribute~):

#+begin_src emacs-lisp
;; Main typeface
(set-face-attribute 'default nil :family "DejaVu Sans Mono" :height 110)

;; Proportionately spaced typeface
(set-face-attribute 'variable-pitch nil :family "DejaVu Serif" :height 1.0)

;; Monospaced typeface
(set-face-attribute 'fixed-pitch nil :family "DejaVu Sans Mono" :height 1.0)
#+end_src

Note the differences in the =:height= property.  The =default= face must
specify an absolute value, which is the point size × 10.  So if you want
to use a font at point size =11=, you set the height to =110=.[fn:: =:height=
values do not need to be rounded to multiples of ten: the likes of =115=
are perfectly valid—some typefaces will change to account for those
finer increments.]  Whereas every other face must have a value that is
relative to the default, represented as a floating point (if you use an
integer, then that means an absolute height).  This is of paramount
importance: it ensures that all fonts can scale gracefully when using
something like the ~text-scale-adjust~ command which only operates on the
base font size (i.e. the ~default~ face's absolute height).

** Custom Org user faces (DIY)
:properties:
:custom_id: h:89f0678d-c5c3-4a57-a526-668b2bb2d7ad
:end:
#+cindex: Org extra faces

Users of ~org-mode~ have the option to configure various keywords and
priority cookies to better match their workflow.  User options are
~org-todo-keyword-faces~ and ~org-priority-faces~.

As those are meant to be custom faces, it is futile to have the themes
guess what each user wants to use, which keywords to target, and so on.
Instead, we can provide guidelines on how to customize things to one's
liking with the intent of retaining the overall aesthetic of the themes.

Please bear in mind that the end result of those is not controlled by
the active Modus theme but by how Org maps faces to its constructs.
Editing those while ~org-mode~ is active requires re-initialization of the
mode with {{{kbd(M-x org-mode-restart)}}} for changes to take effect.

Let us assume you wish to visually differentiate your keywords.  You
have something like this:

#+begin_src emacs-lisp
(setq org-todo-keywords
      '((sequence "TODO(t)" "|" "DONE(D)" "CANCEL(C)")
        (sequence "MEET(m)" "|" "MET(M)")
        (sequence "STUDY(s)" "|" "STUDIED(S)")
        (sequence "WRITE(w)" "|" "WROTE(W)")))
#+end_src

You could then use a variant of the following to inherit from a face
that uses the styles you want and also to preserve the properties
applied by the ~org-todo~ face:

#+begin_src emacs-lisp
(setq org-todo-keyword-faces
      '(("MEET" . '(font-lock-preprocessor-face org-todo))
        ("STUDY" . '(font-lock-variable-name-face org-todo))
        ("WRITE" . '(font-lock-type-face org-todo))))
#+end_src

This will refashion the keywords you specify, while letting the other
items in ~org-todo-keywords~ use their original styles (which are defined
in the ~org-todo~ and ~org-done~ faces).

If you want back the defaults, try specifying just the ~org-todo~ face:

#+begin_src emacs-lisp
(setq org-todo-keyword-faces
      '(("MEET" . org-todo)
        ("STUDY" . org-todo)
        ("WRITE" . org-todo)))
#+end_src

When you inherit from multiple faces, you need to quote the list as
shown further above.  The order is important: the last item is applied
over the previous ones.  If you do not want to blend multiple faces, you
do not need a quoted list.  A pattern of =keyword . face= will suffice.

Both approaches can be used simultaneously, as illustrated in this
configuration of the priority cookies:

#+begin_src emacs-lisp
(setq org-priority-faces
      '((?A . '(org-scheduled-today org-priority))
        (?B . org-priority)
        (?C . '(shadow org-priority))))
#+end_src

To find all the faces that are loaded in your current Emacs session, use
{{{kbd(M-x list-faces-display)}}}.  Try {{{kbd(M-x describe-variable)}}} as well and
then specify the name of each of those Org variables demonstrated above.
Their documentation strings will offer you further guidance.

Recall that the themes let you retrieve a color from their palette.  Do
it if you plan to control face attributes.

[[#h:1487c631-f4fe-490d-8d58-d72ffa3bd474][Custom face specs using the themes' palette]].

[[#h:02e25930-e71a-493d-828a-8907fc80f874][Check color combinations]].

** Measure color contrast (DIY)
:properties:
:custom_id: h:02e25930-e71a-493d-828a-8907fc80f874
:end:
#+findex: modus-themes-contrast
#+findex: modus-themes-wcag-formula
#+cindex: Color contrast

The themes provide the functions ~modus-themes-wcag-formula~ and
~modus-themes-contrast~.  The former is a direct implementation of the
WCAG formula: <https://www.w3.org/TR/WCAG20-TECHS/G18.html>.  It
calculates the relative luminance of a color value that is expressed in
hexadecimal RGB notation.  While the latter function is just a
convenient wrapper for comparing the relative luminance between two
colors.

In practice, one needs to work only with ~modus-themes-contrast~.  It
accepts two color values and returns their contrast ratio.  Values range
from 1 to 21 (lowest to highest).  The themes are designed to always be
equal or higher than 7 for each combination of background and foreground
that they use (this is the WCAG AAA standard---the most demanding of its
kind).

A couple of examples (rounded numbers):

#+begin_src emacs-lisp
;; Pure white with pure green
(modus-themes-contrast "#ffffff" "#00ff00")
;; => 1.37
;; That is an outright inaccessible combo

;; Pure black with pure green
(modus-themes-contrast "#000000" "#00ff00")
;; => 15.3
;; That is is a highly accessible combo
#+end_src

It does not matter which color value comes first.  The ratio is always
the same.

If one does not wish to read all the decimal points, it is possible to
try something like this:

#+begin_src emacs-lisp
(format "%0.2f" (modus-themes-contrast "#000000" "#00ff00"))
#+end_src

While it is fine to perform such calculations on a case-by-case basis,
it is preferable to implement formulas and tables for more demanding
tasks.  Such instruments are provided by ~org-mode~ or ~orgtbl-mode~, both
of which are built into Emacs.  Below is such a table that derives the
contrast ratio of all colors in the first column (pure red, green, blue)
relative to the color specified in the first row of the second column
(pure white) and rounds the results:

#+begin_example
|         | #ffffff |
|---------+---------|
| #ff0000 |    4.00 |
| #00ff00 |    1.37 |
| #0000ff |    8.59 |
#+tblfm: $2='(modus-themes-contrast $1 @1$2);%0.2f
#+end_example

To measure color contrast one needs to start from a known value.  This
typically is the background.  The Modus themes define an expanded
palette in large part because certain colors are only meant to be used
in combination with some others.  Consult the source code for the
minutia and relevant commentary.

Such knowledge may prove valuable while attempting to override some of
the themes' colors: [[#h:307d95dd-8dbd-4ece-a543-10ae86f155a6][Override colors]].

** Load theme depending on time of day
:properties:
:custom_id: h:1d1ef4b4-8600-4a09-993c-6de3af0ddd26
:end:

While we do provide ~modus-themes-toggle~ to manually switch between the
themes, users may also set up their system to perform such a task
automatically at sunrise and sunset.

This can be accomplished by specifying the coordinates of one's location
using the built-in {{{file(solar.el)}}} and then configuring the =circadian=
package:

#+begin_src emacs-lisp
(use-package solar                      ; built-in
  :config
  (setq calendar-latitude 35.17
        calendar-longitude 33.36))

(use-package circadian                  ; you need to install this
  :ensure
  :after solar
  (setq circadian-themes '((:sunrise . modus-operandi)
                           (:sunset  . modus-vivendi)))
  (circadian-setup))
#+end_src

** A theme-agnostic hook for theme loading (DIY)
:properties:
:custom_id: h:86f6906b-f090-46cc-9816-1fe8aeb38776
:end:

The themes are designed with the intent to be useful to Emacs users of
varying skill levels, from beginners to experts.  This means that we try
to make things easier by not expecting anyone reading this document to
be proficient in Emacs Lisp or programming in general.

Such a case is with the use of the ~modus-themes-after-load-theme-hook~,
which runs after ~modus-themes-toggle~, ~modus-themes-load-operandi~, or
~modus-themes-load-vivendi~ is evaluated.  We recommend using that hook
for advanced customizations, because (1) we know for sure that it is
available once the themes are loaded, and (2) anyone consulting this
manual, especially the sections on enabling and loading the themes, will
be in a good position to benefit from that hook.

Advanced users who have a need to switch between the Modus themes and
other items will find that such a hook does not meet their requirements:
it only works with the Modus themes and only with the aforementioned
functions.

A theme-agnostic setup can be configured thus:

#+begin_src emacs-lisp
(defvar after-enable-theme-hook nil
   "Normal hook run after enabling a theme.")

(defun run-after-enable-theme-hook (&rest _args)
   "Run `after-enable-theme-hook'."
   (run-hooks 'after-enable-theme-hook))

(advice-add 'enable-theme :after #'run-after-enable-theme-hook)
#+end_src

This creates the ~after-enable-theme-hook~ and makes it run after each
call to ~enable-theme~, which means that it will work for all themes and
also has the benefit that it does not depend on functions such as
~modus-themes-toggle~ and the others mentioned above.  ~enable-theme~ is
called internally by ~load-theme~, so the hook works everywhere.

Now this specific piece of Elisp may be simple for experienced users,
but it is not easy to read for newcomers, including the author of the
Modus themes for the first several months of their time as an Emacs
user.  Hence our hesitation to recommend it as part of the standard
setup of the Modus themes (it is generally a good idea to understand
what the implications are of advising a function).

* Face coverage
:properties:
:custom_id: h:a9c8f29d-7f72-4b54-b74b-ddefe15d6a19
:end:

The Modus themes try to provide as close to full face coverage as
possible.  This is necessary to ensure a consistently accessible reading
experience across all available interfaces.

** Full support for packages or face groups
:properties:
:alt_title: Supported packages
:description: Full list of covered face groups
:custom_id: h:60ed4275-60d6-49f8-9287-9a64e54bea0e
:end:
#+cindex: Explicitly supported packages

This list will always be updated to reflect the current state of the
project.  The idea is to offer an overview of the known status of all
affected face groups.  The items with an appended asterisk =*= tend to
have lots of extensions, so the "full support" may not be 100% true…

+ ace-window
+ ag
+ alert
+ all-the-icons
+ annotate
+ anzu
+ apropos
+ apt-sources-list
+ artbollocks-mode
+ auctex and TeX
+ auto-dim-other-buffers
+ avy
+ awesome-tray
+ bbdb
+ binder
+ bm
+ bongo
+ boon
+ breakpoint (provided by the built-in {{{file(gdb-mi.el)}}} library)
+ buffer-expose
+ calendar and diary
+ calfw
+ centaur-tabs
+ cfrs
+ change-log and log-view (such as ~vc-print-log~, ~vc-print-root-log~)
+ cider
+ circe
+ color-rg
+ column-enforce-mode
+ company-mode*
+ company-posframe
+ compilation-mode
+ completions
+ consult
+ counsel*
+ counsel-css
+ counsel-notmuch
+ counsel-org-capture-string
+ cov
+ cperl-mode
+ csv-mode
+ ctrlf
+ custom (what you get with {{{kbd(M-x customize)}}})
+ dap-mode
+ dashboard (emacs-dashboard)
+ deadgrep
+ debbugs
+ define-word
+ deft
+ dictionary
+ diff-hl
+ diff-mode
+ dim-autoload
+ dir-treeview
+ dired
+ dired-async
+ dired-git
+ dired-git-info
+ dired-narrow
+ dired-subtree
+ diredc
+ diredfl
+ diredp (dired+)
+ disk-usage
+ display-fill-column-indicator-mode
+ doom-modeline
+ dynamic-ruler
+ easy-jekyll
+ easy-kill
+ ebdb
+ ediff
+ eglot
+ el-search
+ eldoc-box
+ elfeed
+ elfeed-score
+ emms
+ enhanced-ruby-mode
+ epa
+ equake
+ erc
+ eros
+ ert
+ eshell
+ eshell-fringe-status
+ eshell-git-prompt
+ eshell-prompt-extras (epe)
+ eshell-syntax-highlighting
+ evil* (evil-mode)
+ evil-goggles
+ evil-snipe
+ evil-visual-mark-mode
+ eww
+ exwm
+ eyebrowse
+ fancy-dabbrev
+ flycheck
+ flycheck-color-mode-line
+ flycheck-indicator
+ flycheck-posframe
+ flymake
+ flyspell
+ flyspell-correct
+ flx
+ freeze-it
+ frog-menu
+ focus
+ fold-this
+ font-lock (generic syntax highlighting)
+ forge
+ fountain (fountain-mode)
+ geiser
+ git-commit
+ git-gutter (and variants)
+ git-lens
+ git-rebase
+ git-timemachine
+ git-walktree
+ gnus
+ golden-ratio-scroll-screen
+ helm*
+ helm-ls-git
+ helm-switch-shell
+ helm-xref
+ helpful
+ highlight-blocks
+ highlight-defined
+ highlight-escape-sequences (~hes-mode~)
+ highlight-indentation
+ highlight-numbers
+ highlight-symbol
+ highlight-tail
+ highlight-thing
+ hl-defined
+ hl-fill-column
+ hl-line-mode
+ hl-todo
+ hydra
+ hyperlist
+ ibuffer
+ icomplete
+ icomplete-vertical
+ ido-mode
+ iedit
+ iflipb
+ imenu-list
+ indium
+ info
+ info-colors
+ interaction-log
+ ioccur
+ isearch, occur, etc.
+ isl (isearch-light)
+ ivy*
+ ivy-posframe
+ jira (org-jira)
+ journalctl-mode
+ js2-mode
+ julia
+ jupyter
+ kaocha-runner
+ keycast
+ line numbers (~display-line-numbers-mode~ and global variant)
+ lsp-mode
+ lsp-ui
+ macrostep
+ magit
+ magit-imerge
+ make-mode
+ man
+ marginalia
+ markdown-mode
+ markup-faces (~adoc-mode~)
+ mentor
+ messages
+ minibuffer-line
+ minimap
+ mmm-mode
+ modeline
+ mood-line
+ moody
+ mpdel
+ mu4e
+ mu4e-conversation
+ multiple-cursors
+ neotree
+ no-emoji
+ notmuch
+ num3-mode
+ nxml-mode
+ objed
+ orderless
+ org*
+ org-journal
+ org-noter
+ org-pomodoro
+ org-recur
+ org-roam
+ org-superstar
+ org-table-sticky-header
+ org-tree-slide
+ org-treescope
+ origami
+ outline-mode
+ outline-minor-faces
+ package (what you get with {{{kbd(M-x list-packages)}}})
+ page-break-lines
+ paradox
+ paren-face
+ parrot
+ pass
+ pdf-tools
+ persp-mode
+ perspective
+ phi-grep
+ phi-search
+ pkgbuild-mode
+ pomidor
+ popup
+ powerline
+ powerline-evil
+ prism ([[#h:a94272e0-99da-4149-9e80-11a7e67a2cf2][Note for prism.el]])
+ proced
+ prodigy
+ quick-peek
+ racket-mode
+ rainbow-blocks
+ rainbow-identifiers
+ rainbow-delimiters
+ rcirc
+ recursion-indicator
+ regexp-builder (also known as ~re-builder~)
+ rg (rg.el)
+ ripgrep
+ rmail
+ ruler-mode
+ sallet
+ selectrum
+ selectrum-prescient
+ semantic
+ sesman
+ shell-script-mode
+ shortdoc
+ show-paren-mode
+ shr
+ side-notes
+ sieve-mode
+ skewer-mode
+ smart-mode-line
+ smartparens
+ smerge
+ solaire
+ spaceline
+ speedbar
+ spell-fu
+ spray
+ stripes
+ suggest
+ switch-window
+ swiper
+ swoop
+ sx
+ symbol-overlay
+ syslog-mode
+ table (built-in table.el)
+ telephone-line
+ terraform-mode
+ term
+ tomatinho
+ transient (pop-up windows such as Magit's)
+ trashed
+ treemacs
+ tty-menu
+ tuareg
+ typescript
+ undo-tree
+ vc (built-in mode line status for version control)
+ vc-annotate (the out put of {{{kbd(C-x v g)}}})
+ vdiff
+ vimish-fold
+ visible-mark
+ visual-regexp
+ volatile-highlights
+ vterm
+ wcheck-mode
+ web-mode
+ wgrep
+ which-function-mode
+ which-key
+ whitespace-mode
+ window-divider-mode
+ winum
+ writegood-mode
+ woman
+ xah-elisp-mode
+ xref
+ xterm-color (and ansi-colors)
+ yaml-mode
+ yasnippet
+ ztree

Plus many other miscellaneous faces that are provided by the upstream
GNU Emacs distribution.

** Indirectly covered packages
:properties:
:custom_id: h:2cb359c7-3a84-4262-bab3-dcdc1d0034d7
:end:
#+cindex: Implicitly supported packages

These do not require any extra styles because they are configured to
inherit from some basic faces.  Please confirm.

+ edit-indirect
+ evil-owl
+ fortran-mode
+ goggles
+ i3wm-config-mode
+ perl-mode
+ php-mode
+ rjsx-mode
+ swift-mode
+ tab-bar-echo-area

* Notes for individual packages
:properties:
:custom_id: h:4c4d901a-84d7-4f20-bd99-0808c2b06eba
:end:

This section covers information that may be of interest to users of
individual packages.

** Note for display-fill-column-indicator-mode
:properties:
:custom_id: h:2a602816-bc1b-45bf-9675-4cbbd7bf6cab
:end:

While designing the style for ~display-fill-column-indicator-mode~, we
stayed close to the mode's defaults: to apply a subtle foreground color
to the ~fill-column-indicator~ face, which blends well with the rest of
theme and is consistent with the role of that mode.  This is to not
upset the expectations of users.

Nevertheless, ~display-fill-column-indicator-mode~ has some known
limitations pertaining to its choice of using typographic characters to
draw its indicator.  What should be a continuous vertical line might
appear as a series of dashes in certain contexts or under specific
conditions: a non-default value for ~line-spacing~, scaled and/or
variable-pitch headings have been observed to cause this effect.

Given that we cannot control such factors, it may be better for affected
users to deviate from the default style of the ~fill-column-indicator~
face.  Instead of setting a foreground color, one could use a background
and have the foreground be indistinguishable from it.  For example:

#+begin_src emacs-lisp
(modus-themes-with-colors
  (custom-set-faces
   `(fill-column-indicator ((,class :background ,bg-inactive
                                    :foreground ,bg-inactive)))))
#+end_src

[[#h:51ba3547-b8c8-40d6-ba5a-4586477fd4ae][Face specs at scale using the themes' palette]].

** Note for mmm-mode.el background colors
:properties:
:custom_id: h:99cf0d6c-e478-4e26-9932-3bf3427d13f6
:end:

The faces used by {{{file(mmm-mode.el)}}} are expected to have a colorful
background, while they should not touch any foreground value.  The idea
is that they must not interfere with existing fontification.  Those
background colors need to be distinct from each other, such as an
unambiguous red juxtaposed with a clear blue.

While this design may be internally consistent with the raison d'être of
that library, it inevitably produces inaccessible color combinations.

There are two competing goals at play:

1. Legibility of the text, understood as the contrast ratio between the
   background and the foreground.

2. Semantic precision of each face which entails faithfulness to
   color-coding of the underlying background.

As the Modus themes are designed with the express purpose of conforming
with the first point, we have to forgo the apparent color-coding of the
background elements.  Instead we use subtle colors that do not undermine
the legibility of the affected text while they still offer a sense of
added context.

Users who might prefer to fall below the minimum 7:1 contrast ratio in
relative luminance (the accessibility target we conform with), can opt
to configure the relevant faces on their own.

[[#h:51ba3547-b8c8-40d6-ba5a-4586477fd4ae][Face specs at scale using the themes' palette]].

This example uses more vivid background colors, though it comes at the
very high cost of degraded legibility.

#+begin_src emacs-lisp
(modus-themes-with-colors
  (custom-set-faces
   `(mmm-cleanup-submode-face ((,class :background ,yellow-refine-bg)))
   `(mmm-code-submode-face ((,class :background ,bg-active)))
   `(mmm-comment-submode-face ((,class :background ,blue-refine-bg)))
   `(mmm-declaration-submode-face ((,class :background ,cyan-refine-bg)))
   `(mmm-default-submode-face ((,class :background ,bg-alt)))
   `(mmm-init-submode-face ((,class :background ,magenta-refine-bg)))
   `(mmm-output-submode-face ((,class :background ,red-refine-bg)))
   `(mmm-special-submode-face ((,class :background ,green-refine-bg)))))
#+end_src

** Note for prism.el
:properties:
:alt_title: Note for prism
:custom_id: h:a94272e0-99da-4149-9e80-11a7e67a2cf2
:end:

This package by Adam Porter, aka "alphapapa" or "github-alphapapa",
implements an alternative to the typical coloration of code.  Instead of
highlighting the syntactic constructs, it applies color to different
levels of depth in the code structure.

As {{{file(prism.el)}}} offers a broad range of customisations, we cannot
style it directly at the theme level: that would run contrary to the
spirit of the package.  Instead, we may offer preset color schemes.
Those should offer a starting point for users to adapt to their needs.

In the following code snippets, we employ the ~modus-themes-with-colors~
macro: [[#h:51ba3547-b8c8-40d6-ba5a-4586477fd4ae][Face specs at scale using the themes' palette]].

These are the minimum recommended settings with 16 colors:

#+begin_src emacs-lisp
(setq prism-num-faces 16)

(prism-set-colors
  :desaturations '(0) ; do not change---may lower the contrast ratio
  :lightens '(0)      ; same
  :colors (modus-themes-with-colors
            (list fg-main
                  magenta
                  cyan-alt-other
                  magenta-alt-other
                  blue
                  magenta-alt
                  cyan-alt
                  red-alt-other
                  green
                  fg-main
                  cyan
                  yellow
                  blue-alt
                  red-alt
                  green-alt-other
                  fg-special-warm)))
#+end_src

With 8 colors:

#+begin_src emacs-lisp
(setq prism-num-faces 8)

(prism-set-colors
  :desaturations '(0) ; do not change---may lower the contrast ratio
  :lightens '(0)      ; same
  :colors (modus-themes-with-colors
            (list fg-special-cold
                  magenta
                  magenta-alt-other
                  cyan-alt-other
                  fg-main
                  blue-alt
                  red-alt-other
                  cyan)))
#+end_src

And this is with 4 colors, which produces results that are the closest
to the themes' default aesthetic:

#+begin_src emacs-lisp
(setq prism-num-faces 4)

(prism-set-colors
  :desaturations '(0) ; do not change---may lower the contrast ratio
  :lightens '(0)      ; same
  :colors (modus-themes-with-colors
            (list fg-main
                  cyan-alt-other
                  magenta-alt-other
                  magenta)))
#+end_src

If you need to apply desaturation and lightening, you can use what the
{{{file(prism.el)}}} documentation recommends, like this (adapting to the
examples with the 4, 8, 16 colors):

#+begin_src emacs-lisp
(prism-set-colors
  :desaturations (cl-loop for i from 0 below 16 collect (* i 2.5))
  :lightens (cl-loop for i from 0 below 16 collect (* i 2.5))
  :colors (modus-themes-with-colors
            (list fg-main
                  cyan-alt-other
                  magenta-alt-other
                  magenta)))
#+end_src

** Note on company-mode overlay pop-up
:properties:
:custom_id: h:20cef8c4-d11f-4053-8b2c-2872925780b1
:end:

By default, the ~company-mode~ pop-up that lists completion candidates is
drawn using an overlay.  This creates alignment issues every time it is
placed above a piece of text that has a different height than the
default.

The solution recommended by the project's maintainer is to use an
alternative front-end for drawing the pop-up which draws child frames
instead of overlays.[fn::
https://github.com/company-mode/company-mode/issues/1010][fn::
https://github.com/tumashu/company-posframe/]

** Note for ERC escaped color sequences
:properties:
:custom_id: h:98bdf319-1e32-4469-8a01-771200fba65c
:end:

The built-in IRC client ~erc~ has the ability to colorise any text using
escape sequences that start with =^C= (inserted with {{{kbd(C-q C-c)}}}) and are
followed by a number for the foreground and background.[fn:: This page
explains the basics, though it is not specific to Emacs:
https://www.mirc.com/colors.html] Possible numbers are 0-15, with the
first entry being the foreground and the second the background,
separated by a comma.  Like this =^C1,6=.  The minimum setup is this:

#+begin_src emacs-lisp
(add-to-list 'erc-modules 'irccontrols)
(setq erc-interpret-controls-p t
      erc-interpret-mirc-color t)
#+end_src

As this allows users the chance to make arbitrary combinations, it is
impossible to guarantee a consistently high contrast ratio.  All we can
we do is provide guidance on the combinations that satisfy the
accessibility standard of the themes:

+ Modus Operandi :: Use foreground color 1 for all backgrounds from
  2-15.  Like so: {{{kbd(C-q C-c1,N)}}} where =N= is the background.

+ Modus Vivendi :: Use foreground color 0 for all backgrounds from
  2-13.  Use foreground =1= for backgrounds 14, 15.

Colors 0 and 1 are white and black respectively.  So combine them
together, if you must.

** Note for powerline or spaceline
:properties:
:custom_id: h:9130a8ba-d8e3-41be-a58b-3cb1eb7b6d17
:end:

Both Powerline and Spaceline package users will likely need to use the
command ~powerline-reset~ whenever they make changes to their themes
and/or modeline setup.

** Note on SHR colors
:properties:
:custom_id: h:4cc767dc-ffef-4c5c-9f10-82eb7b8921bf
:end:

Emacs' HTML rendering library ({{{file(shr.el)}}}) may need explicit
configuration to respect the theme's colors instead of whatever
specifications the webpage provides.

Consult {{{kbd(C-h v shr-use-colors)}}}.

** Note for Helm grep
:properties:
:custom_id: h:d28879a2-8e4b-4525-986e-14c0f873d229
:end:

There is one face from the Helm package that is meant to highlight the
matches of a grep or grep-like command (=ag= or =ripgrep=).  It is
~helm-grep-match~.  However, this face can only apply when the user does
not pass =--color=always= as a command-line option for their command.

Here is the docstring for that face, which is defined in the
{{{file(helm-grep.el)}}} library (you can always visit the source code with
{{{kbd(M-x find-library)}}}).

#+begin_quote
Face used to highlight grep matches.  Have no effect when grep backend
use "--color="
#+end_quote

The user must either remove =--color= from the flags passed to the grep
function, or explicitly use =--color=never= (or equivalent).  Helm
provides user-facing customization options for controlling the grep
function's parameters, such as ~helm-grep-default-command~ and
~helm-grep-git-grep-command~.

When =--color=always= is in effect, the grep output will use red text in
bold letter forms to present the matching part in the list of
candidates.  That style still meets the contrast ratio target of >= 7:1
(accessibility standard WCAG AAA), because it draws the reference to
ANSI color number 1 (red) from the already-supported array of
~ansi-color-names-vector~.

** Note on vc-annotate-background-mode
:properties:
:custom_id: h:5095cbd1-e17a-419c-93e8-951c186362a3
:end:

Due to the unique way ~vc-annotate~ ({{{kbd(C-x v g)}}}) applies colors, support
for its background mode (~vc-annotate-background-mode~) is disabled at the
theme level.

Normally, such a drastic measure should not belong in a theme: assuming
the user's preferences is bad practice.  However, it has been deemed
necessary in the interest of preserving color contrast accessibility
while still supporting a useful built-in tool.

If there actually is a way to avoid such a course of action, without
prejudice to the accessibility standard of this project, then please
report as much or send patches ([[#h:9c3cd842-14b7-44d7-84b2-a5c8bc3fc3b1][Contributing]]).

** Note on pdf-tools link hints
:properties:
:custom_id: h:2659d13e-b1a5-416c-9a89-7c3ce3a76574
:end:

Hints are drawn by [[https://imagemagick.org/][ImageMagick]], not Emacs, i.e., ImageMagick doesn't
know about the hint face unless you tell ImageMagick about it. By
default, only the foreground and background color attributes are
passed. The below snippet adds to those the various font attributes.  As
it queries various faces, specifically ~pdf-links-read-link~ and the faces
it inherits, it needs to be added to your initialization file after
you've customized any faces.

#+begin_src emacs-lisp
(use-package pdf-links
  :config
  (let ((spec
         (apply #'append
                (mapcar
                 (lambda (name)
                   (list name
                         (face-attribute 'pdf-links-read-link
                                         name nil 'default)))
                 '(:family :width :weight :slant)))))
    (setq pdf-links-read-link-convert-commands
          `("-density"    "96"
            "-family"     ,(plist-get spec :family)
            "-stretch"    ,(let* ((width (plist-get spec :width))
                                  (name (symbol-name width)))
                             (replace-regexp-in-string "-" ""
                                                       (capitalize name)))
            "-weight"     ,(pcase (plist-get spec :weight)
                             ('ultra-light "Thin")
                             ('extra-light "ExtraLight")
                             ('light       "Light")
                             ('semi-bold   "SemiBold")
                             ('bold        "Bold")
                             ('extra-bold  "ExtraBold")
                             ('ultra-bold  "Black")
                             (_weight      "Normal"))
            "-style"      ,(pcase (plist-get spec :slant)
                             ('italic  "Italic")
                             ('oblique "Oblique")
                             (_slant   "Normal"))
            "-pointsize"  "%P"
            "-undercolor" "%f"
            "-fill"       "%b"
            "-draw"       "text %X,%Y '%c'"))))
#+end_src

* Contributing
:properties:
:custom_id: h:9c3cd842-14b7-44d7-84b2-a5c8bc3fc3b1
:end:

This section documents the canonical sources of the themes and the ways
in which you can contribute to their ongoing development.

** Sources of the themes
:properties:
:custom_id: h:89504f1c-c9a1-4bd9-ab39-78fd0eddb47c
:end:
#+cindex: Sources of the themes

The ~modus-operandi~ and ~modus-vivendi~ themes are built into Emacs.
Currently they are in Emacs' git main branch (trunk), which is tracking
the next development release target.

The source code of the themes is [[https://gitlab.com/protesilaos/modus-themes/][available on Gitlab]], for the time
being.  A [[https://github.com/protesilaos/modus-themes/][mirror on Github]] is also on offer.

An HTML version of this manual is provided as an extension of the
[[https://protesilaos.com/modus-themes/][author's personal website]] (does not rely on any non-free code).

** Issues you can help with
:properties:
:custom_id: h:6536c8d5-3f98-43ab-a787-b94120e735e8
:end:
#+cindex: Contributing

A few tasks you can help with:

+ Suggest refinements to packages that are covered.
+ Report packages not covered thus far.
+ Report bugs, inconsistencies, shortcomings.
+ Help expand the documentation of covered-but-not-styled packages.
+ Suggest refinements to the color palette.
+ Help expand this document or any other piece of documentation.
+ Merge requests for code refinements.

[[#h:111773e2-f26f-4b68-8c4f-9794ca6b9633][Patches require copyright assignment to the FSF]].

It is preferable that your feedback includes some screenshots, GIFs, or
short videos, as well as further instructions to reproduce a given
setup.  Though this is not a requirement.

Whatever you do, bear in mind the overarching objective of the Modus
themes: to keep a contrast ratio that is greater or equal to 7:1 between
background and foreground colors.  If a compromise is ever necessary
between aesthetics and accessibility, it shall always be made in the
interest of the latter.

** Patches require copyright assignment to the FSF
:properties:
:custom_id: h:111773e2-f26f-4b68-8c4f-9794ca6b9633
:end:

Code contributions are most welcome.  For any major edit (more than 15
lines, or so, in aggregate per person), you need to make a copyright
assignment to the Free Software Foundation.  This is necessary because
the themes are part of the upstream Emacs distribution: the FSF must at
all times be in a position to enforce the GNU General Public License.

Copyright assignment is a simple process.  Check the request form below
(please adapt it accordingly).  You must write an email to the address
mentioned in the form and then wait for the FSF to send you a legal
agreement.  Sign the document and file it back to them.  This could all
happen via email and take about a week.  You are encouraged to go
through this process.  You only need to do it once.  It will allow you
to make contributions to Emacs in general.

#+begin_example text
Please email the following information to assign@gnu.org, and we
will send you the assignment form for your past and future changes.

Please use your full legal name (in ASCII characters) as the subject
line of the message.
----------------------------------------------------------------------
REQUEST: SEND FORM FOR PAST AND FUTURE CHANGES

[What is the name of the program or package you're contributing to?]

GNU Emacs

[Did you copy any files or text written by someone else in these changes?
Even if that material is free software, we need to know about it.]

Copied a few snippets from the same files I edited.  Their author,
Protesilaos Stavrou, has already assigned copyright to the Free Software
Foundation.

[Do you have an employer who might have a basis to claim to own
your changes?  Do you attend a school which might make such a claim?]


[For the copyright registration, what country are you a citizen of?]


[What year were you born?]


[Please write your email address here.]


[Please write your postal address here.]





[Which files have you changed so far, and which new files have you written
so far?]

#+end_example

* Acknowledgements
:properties:
:custom_id: h:95c3da23-217f-404e-b5f3-56c75760ebcf
:end:
#+cindex: Contributors

The Modus themes are a collective effort.  Every bit of work matters.

+ Author/maintainer :: Protesilaos Stavrou.

+ Contributions to code or documentation :: Anders Johansson, Basil
  L.{{{space()}}} Contovounesios, Carlo Zancanaro, Eli Zaretskii, Kostadin
  Ninev, Madhavan Krishnan, Markus Beppler, Matthew Stevenson, Nicolas
  De Jaeghere, Shreyas Ragavan, Stefan Kangas, Vincent Murphy, Xinglu
  Chen.

+ Ideas and user feedback :: Aaron Jensen, Adam Spiers, Adrian Manea,
  Alex Griffin, Alex Peitsinis, Alexey Shmalko, Alok Singh, Anders
  Johansson, André Alexandre Gomes, Arif Rezai, Basil L.{{{space()}}}
  Contovounesios, Burgess Chang, Christian Tietze, Christopher Dimech,
  Damien Cassou, Daniel Mendler, Dario Gjorgjevski, David Edmondson,
  Davor Rotim, Divan Santana, Gerry Agbobada, Gianluca Recchia, Gustavo
  Barros, Hörmetjan Yiltiz, Ilja Kocken, Iris Garcia, Jeremy Friesen,
  John Haman, Joshua O'Connor, Kevin Fleming, Kostadin Ninev, Len Trigg,
  Manuel Uberti, Mark Burton, Markus Beppler, Michael Goldenberg, Morgan
  Smith, Murilo Pereira, Nicolas De Jaeghere, Paul Poloskov, Pete
  Kazmier, Peter Wu, Philip K., Pierre Téchoueyres, Roman Rudakov, Ryan
  Phillips, Sam Kleinman, Shreyas Ragavan, Simon Pugnet, Tassilo Horn,
  Thibaut Verron, Trey Merkley, Togan Muftuoglu, Toon Claes, Uri Sharf,
  Utkarsh Singh, Vincent Foley.  As well as users: Ben, CsBigDataHub1,
  Emacs Contrib, Eugene, Fourchaux, Fredrik, Moesasji, Nick, TheBlob42,
  bepolymathe, doolio, fleimgruber, iSeeU, jixiuf, okamsn.

+ Packaging :: Basil L.{{{space()}}} Contovounesios, Eli Zaretskii, Glenn
  Morris, Mauro Aranda, Richard Stallman, Stefan Kangas (core Emacs),
  Stefan Monnier (GNU Elpa), André Alexandre Gomes, Dimakakos Dimos,
  Morgan Smith, Nicolas Goaziou (Guix), Dhavan Vaidya (Debian).

+ Inspiration for certain features :: Bozhidar Batsov (zenburn-theme),
  Fabrice Niessen (leuven-theme).

Special thanks, in no particular order, to Manuel Uberti and Omar
Antolín Camarena for their long time contributions and insightful
commentary.

* Meta
:properties:
:custom_id: h:13752581-4378-478c-af17-165b6e76bc1b
:end:
#+cindex: Development notes

If you are curious about the principles that govern the development of
this project read the essay [[https://protesilaos.com/codelog/2020-03-17-design-modus-themes-emacs/][On the design of the Modus themes]]
(2020-03-17).

Here are some more publications for those interested in the kind of work
that goes into this project (sometimes the commits also include details
of this sort):

+ [[https://protesilaos.com/codelog/2020-05-10-modus-operandi-palette-review/][Modus Operandi theme subtle palette review]] (2020-05-10)
+ [[https://protesilaos.com/codelog/2020-06-13-modus-vivendi-palette-review/][Modus Vivendi theme subtle palette review]] (2020-06-13)
+ [[https://protesilaos.com/codelog/2020-07-04-modus-themes-faint-colours/][Modus themes: new "faint syntax" option]] (2020-07-04)
+ [[https://protesilaos.com/codelog/2020-07-08-modus-themes-nuanced-colours/][Modus themes: major review of "nuanced" colours]] (2020-07-08)
+ [[https://protesilaos.com/codelog/2020-09-14-modus-themes-review-blues/][Modus themes: review of blue colours]] (2020-09-14)
+ [[https://protesilaos.com/codelog/2020-12-27-modus-themes-review-rainbow-delimiters/][Modus themes: review rainbow-delimiters faces]] (2020-12-27)
+ [[https://protesilaos.com/codelog/2021-01-11-modus-themes-review-select-faint-colours/][Modus themes: review of select "faint" colours]] (2021-01-11)
+ [[https://protesilaos.com/codelog/2021-02-25-modus-themes-diffs-deuteranopia/][The Modus themes now cover deuteranopia in diffs]] (2021-02-25)

And here are the canonical sources of this project's documentation:

+ Manual :: <https://protesilaos.com/modus-themes>
+ Change Log :: <https://protesilaos.com/modus-themes-changelog>
+ Screenshots :: <https://protesilaos.com/modus-themes-pictures>

* GNU Free Documentation License
:properties:
:appendix: t
:custom_id: h:3077c3d2-7f90-4228-8f0a-73124f4026f6
:end:

#+texinfo: @include doclicense.texi

#+begin_export html

                GNU Free Documentation License
                 Version 1.3, 3 November 2008


 Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
     <https://fsf.org/>
 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.

0. PREAMBLE

The purpose of this License is to make a manual, textbook, or other
functional and useful document "free" in the sense of freedom: to
assure everyone the effective freedom to copy and redistribute it,
with or without modifying it, either commercially or noncommercially.
Secondarily, this License preserves for the author and publisher a way
to get credit for their work, while not being considered responsible
for modifications made by others.

This License is a kind of "copyleft", which means that derivative
works of the document must themselves be free in the same sense.  It
complements the GNU General Public License, which is a copyleft
license designed for free software.

We have designed this License in order to use it for manuals for free
software, because free software needs free documentation: a free
program should come with manuals providing the same freedoms that the
software does.  But this License is not limited to software manuals;
it can be used for any textual work, regardless of subject matter or
whether it is published as a printed book.  We recommend this License
principally for works whose purpose is instruction or reference.


1. APPLICABILITY AND DEFINITIONS

This License applies to any manual or other work, in any medium, that
contains a notice placed by the copyright holder saying it can be
distributed under the terms of this License.  Such a notice grants a
world-wide, royalty-free license, unlimited in duration, to use that
work under the conditions stated herein.  The "Document", below,
refers to any such manual or work.  Any member of the public is a
licensee, and is addressed as "you".  You accept the license if you
copy, modify or distribute the work in a way requiring permission
under copyright law.

A "Modified Version" of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.

A "Secondary Section" is a named appendix or a front-matter section of
the Document that deals exclusively with the relationship of the
publishers or authors of the Document to the Document's overall
subject (or to related matters) and contains nothing that could fall
directly within that overall subject.  (Thus, if the Document is in
part a textbook of mathematics, a Secondary Section may not explain
any mathematics.)  The relationship could be a matter of historical
connection with the subject or with related matters, or of legal,
commercial, philosophical, ethical or political position regarding
them.

The "Invariant Sections" are certain Secondary Sections whose titles
are designated, as being those of Invariant Sections, in the notice
that says that the Document is released under this License.  If a
section does not fit the above definition of Secondary then it is not
allowed to be designated as Invariant.  The Document may contain zero
Invariant Sections.  If the Document does not identify any Invariant
Sections then there are none.

The "Cover Texts" are certain short passages of text that are listed,
as Front-Cover Texts or Back-Cover Texts, in the notice that says that
the Document is released under this License.  A Front-Cover Text may
be at most 5 words, and a Back-Cover Text may be at most 25 words.

A "Transparent" copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
straightforwardly with generic text editors or (for images composed of
pixels) generic paint programs or (for drawings) some widely available
drawing editor, and that is suitable for input to text formatters or
for automatic translation to a variety of formats suitable for input
to text formatters.  A copy made in an otherwise Transparent file
format whose markup, or absence of markup, has been arranged to thwart
or discourage subsequent modification by readers is not Transparent.
An image format is not Transparent if used for any substantial amount
of text.  A copy that is not "Transparent" is called "Opaque".

Examples of suitable formats for Transparent copies include plain
ASCII without markup, Texinfo input format, LaTeX input format, SGML
or XML using a publicly available DTD, and standard-conforming simple
HTML, PostScript or PDF designed for human modification.  Examples of
transparent image formats include PNG, XCF and JPG.  Opaque formats
include proprietary formats that can be read and edited only by
proprietary word processors, SGML or XML for which the DTD and/or
processing tools are not generally available, and the
machine-generated HTML, PostScript or PDF produced by some word
processors for output purposes only.

The "Title Page" means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the material
this License requires to appear in the title page.  For works in
formats which do not have any title page as such, "Title Page" means
the text near the most prominent appearance of the work's title,
preceding the beginning of the body of the text.

The "publisher" means any person or entity that distributes copies of
the Document to the public.

A section "Entitled XYZ" means a named subunit of the Document whose
title either is precisely XYZ or contains XYZ in parentheses following
text that translates XYZ in another language.  (Here XYZ stands for a
specific section name mentioned below, such as "Acknowledgements",
"Dedications", "Endorsements", or "History".)  To "Preserve the Title"
of such a section when you modify the Document means that it remains a
section "Entitled XYZ" according to this definition.

The Document may include Warranty Disclaimers next to the notice which
states that this License applies to the Document.  These Warranty
Disclaimers are considered to be included by reference in this
License, but only as regards disclaiming warranties: any other
implication that these Warranty Disclaimers may have is void and has
no effect on the meaning of this License.

2. VERBATIM COPYING

You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License applies
to the Document are reproduced in all copies, and that you add no
other conditions whatsoever to those of this License.  You may not use
technical measures to obstruct or control the reading or further
copying of the copies you make or distribute.  However, you may accept
compensation in exchange for copies.  If you distribute a large enough
number of copies you must also follow the conditions in section 3.

You may also lend copies, under the same conditions stated above, and
you may publicly display copies.


3. COPYING IN QUANTITY

If you publish printed copies (or copies in media that commonly have
printed covers) of the Document, numbering more than 100, and the
Document's license notice requires Cover Texts, you must enclose the
copies in covers that carry, clearly and legibly, all these Cover
Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
the back cover.  Both covers must also clearly and legibly identify
you as the publisher of these copies.  The front cover must present
the full title with all words of the title equally prominent and
visible.  You may add other material on the covers in addition.
Copying with changes limited to the covers, as long as they preserve
the title of the Document and satisfy these conditions, can be treated
as verbatim copying in other respects.

If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
reasonably) on the actual cover, and continue the rest onto adjacent
pages.

If you publish or distribute Opaque copies of the Document numbering
more than 100, you must either include a machine-readable Transparent
copy along with each Opaque copy, or state in or with each Opaque copy
a computer-network location from which the general network-using
public has access to download using public-standard network protocols
a complete Transparent copy of the Document, free of added material.
If you use the latter option, you must take reasonably prudent steps,
when you begin distribution of Opaque copies in quantity, to ensure
that this Transparent copy will remain thus accessible at the stated
location until at least one year after the last time you distribute an
Opaque copy (directly or through your agents or retailers) of that
edition to the public.

It is requested, but not required, that you contact the authors of the
Document well before redistributing any large number of copies, to
give them a chance to provide you with an updated version of the
Document.


4. MODIFICATIONS

You may copy and distribute a Modified Version of the Document under
the conditions of sections 2 and 3 above, provided that you release
the Modified Version under precisely this License, with the Modified
Version filling the role of the Document, thus licensing distribution
and modification of the Modified Version to whoever possesses a copy
of it.  In addition, you must do these things in the Modified Version:

A. Use in the Title Page (and on the covers, if any) a title distinct
   from that of the Document, and from those of previous versions
   (which should, if there were any, be listed in the History section
   of the Document).  You may use the same title as a previous version
   if the original publisher of that version gives permission.
B. List on the Title Page, as authors, one or more persons or entities
   responsible for authorship of the modifications in the Modified
   Version, together with at least five of the principal authors of the
   Document (all of its principal authors, if it has fewer than five),
   unless they release you from this requirement.
C. State on the Title page the name of the publisher of the
   Modified Version, as the publisher.
D. Preserve all the copyright notices of the Document.
E. Add an appropriate copyright notice for your modifications
   adjacent to the other copyright notices.
F. Include, immediately after the copyright notices, a license notice
   giving the public permission to use the Modified Version under the
   terms of this License, in the form shown in the Addendum below.
G. Preserve in that license notice the full lists of Invariant Sections
   and required Cover Texts given in the Document's license notice.
H. Include an unaltered copy of this License.
I. Preserve the section Entitled "History", Preserve its Title, and add
   to it an item stating at least the title, year, new authors, and
   publisher of the Modified Version as given on the Title Page.  If
   there is no section Entitled "History" in the Document, create one
   stating the title, year, authors, and publisher of the Document as
   given on its Title Page, then add an item describing the Modified
   Version as stated in the previous sentence.
J. Preserve the network location, if any, given in the Document for
   public access to a Transparent copy of the Document, and likewise
   the network locations given in the Document for previous versions
   it was based on.  These may be placed in the "History" section.
   You may omit a network location for a work that was published at
   least four years before the Document itself, or if the original
   publisher of the version it refers to gives permission.
K. For any section Entitled "Acknowledgements" or "Dedications",
   Preserve the Title of the section, and preserve in the section all
   the substance and tone of each of the contributor acknowledgements
   and/or dedications given therein.
L. Preserve all the Invariant Sections of the Document,
   unaltered in their text and in their titles.  Section numbers
   or the equivalent are not considered part of the section titles.
M. Delete any section Entitled "Endorsements".  Such a section
   may not be included in the Modified Version.
N. Do not retitle any existing section to be Entitled "Endorsements"
   or to conflict in title with any Invariant Section.
O. Preserve any Warranty Disclaimers.

If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no material
copied from the Document, you may at your option designate some or all
of these sections as invariant.  To do this, add their titles to the
list of Invariant Sections in the Modified Version's license notice.
These titles must be distinct from any other section titles.

You may add a section Entitled "Endorsements", provided it contains
nothing but endorsements of your Modified Version by various
parties--for example, statements of peer review or that the text has
been approved by an organization as the authoritative definition of a
standard.

You may add a passage of up to five words as a Front-Cover Text, and a
passage of up to 25 words as a Back-Cover Text, to the end of the list
of Cover Texts in the Modified Version.  Only one passage of
Front-Cover Text and one of Back-Cover Text may be added by (or
through arrangements made by) any one entity.  If the Document already
includes a cover text for the same cover, previously added by you or
by arrangement made by the same entity you are acting on behalf of,
you may not add another; but you may replace the old one, on explicit
permission from the previous publisher that added the old one.

The author(s) and publisher(s) of the Document do not by this License
give permission to use their names for publicity for or to assert or
imply endorsement of any Modified Version.


5. COMBINING DOCUMENTS

You may combine the Document with other documents released under this
License, under the terms defined in section 4 above for modified
versions, provided that you include in the combination all of the
Invariant Sections of all of the original documents, unmodified, and
list them all as Invariant Sections of your combined work in its
license notice, and that you preserve all their Warranty Disclaimers.

The combined work need only contain one copy of this License, and
multiple identical Invariant Sections may be replaced with a single
copy.  If there are multiple Invariant Sections with the same name but
different contents, make the title of each such section unique by
adding at the end of it, in parentheses, the name of the original
author or publisher of that section if known, or else a unique number.
Make the same adjustment to the section titles in the list of
Invariant Sections in the license notice of the combined work.

In the combination, you must combine any sections Entitled "History"
in the various original documents, forming one section Entitled
"History"; likewise combine any sections Entitled "Acknowledgements",
and any sections Entitled "Dedications".  You must delete all sections
Entitled "Endorsements".


6. COLLECTIONS OF DOCUMENTS

You may make a collection consisting of the Document and other
documents released under this License, and replace the individual
copies of this License in the various documents with a single copy
that is included in the collection, provided that you follow the rules
of this License for verbatim copying of each of the documents in all
other respects.

You may extract a single document from such a collection, and
distribute it individually under this License, provided you insert a
copy of this License into the extracted document, and follow this
License in all other respects regarding verbatim copying of that
document.


7. AGGREGATION WITH INDEPENDENT WORKS

A compilation of the Document or its derivatives with other separate
and independent documents or works, in or on a volume of a storage or
distribution medium, is called an "aggregate" if the copyright
resulting from the compilation is not used to limit the legal rights
of the compilation's users beyond what the individual works permit.
When the Document is included in an aggregate, this License does not
apply to the other works in the aggregate which are not themselves
derivative works of the Document.

If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one half of
the entire aggregate, the Document's Cover Texts may be placed on
covers that bracket the Document within the aggregate, or the
electronic equivalent of covers if the Document is in electronic form.
Otherwise they must appear on printed covers that bracket the whole
aggregate.


8. TRANSLATION

Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section 4.
Replacing Invariant Sections with translations requires special
permission from their copyright holders, but you may include
translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections.  You may include a
translation of this License, and all the license notices in the
Document, and any Warranty Disclaimers, provided that you also include
the original English version of this License and the original versions
of those notices and disclaimers.  In case of a disagreement between
the translation and the original version of this License or a notice
or disclaimer, the original version will prevail.

If a section in the Document is Entitled "Acknowledgements",
"Dedications", or "History", the requirement (section 4) to Preserve
its Title (section 1) will typically require changing the actual
title.


9. TERMINATION

You may not copy, modify, sublicense, or distribute the Document
except as expressly provided under this License.  Any attempt
otherwise to copy, modify, sublicense, or distribute it is void, and
will automatically terminate your rights under this License.

However, if you cease all violation of this License, then your license
from a particular copyright holder is reinstated (a) provisionally,
unless and until the copyright holder explicitly and finally
terminates your license, and (b) permanently, if the copyright holder
fails to notify you of the violation by some reasonable means prior to
60 days after the cessation.

Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from that
copyright holder, and you cure the violation prior to 30 days after
your receipt of the notice.

Termination of your rights under this section does not terminate the
licenses of parties who have received copies or rights from you under
this License.  If your rights have been terminated and not permanently
reinstated, receipt of a copy of some or all of the same material does
not give you any rights to use it.


10. FUTURE REVISIONS OF THIS LICENSE

The Free Software Foundation may publish new, revised versions of the
GNU Free Documentation License from time to time.  Such new versions
will be similar in spirit to the present version, but may differ in
detail to address new problems or concerns.  See
https://www.gnu.org/licenses/.

Each version of the License is given a distinguishing version number.
If the Document specifies that a particular numbered version of this
License "or any later version" applies to it, you have the option of
following the terms and conditions either of that specified version or
of any later version that has been published (not as a draft) by the
Free Software Foundation.  If the Document does not specify a version
number of this License, you may choose any version ever published (not
as a draft) by the Free Software Foundation.  If the Document
specifies that a proxy can decide which future versions of this
License can be used, that proxy's public statement of acceptance of a
version permanently authorizes you to choose that version for the
Document.

11. RELICENSING

"Massive Multiauthor Collaboration Site" (or "MMC Site") means any
World Wide Web server that publishes copyrightable works and also
provides prominent facilities for anybody to edit those works.  A
public wiki that anybody can edit is an example of such a server.  A
"Massive Multiauthor Collaboration" (or "MMC") contained in the site
means any set of copyrightable works thus published on the MMC site.

"CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0
license published by Creative Commons Corporation, a not-for-profit
corporation with a principal place of business in San Francisco,
California, as well as future copyleft versions of that license
published by that same organization.

"Incorporate" means to publish or republish a Document, in whole or in
part, as part of another Document.

An MMC is "eligible for relicensing" if it is licensed under this
License, and if all works that were first published under this License
somewhere other than this MMC, and subsequently incorporated in whole or
in part into the MMC, (1) had no cover texts or invariant sections, and
(2) were thus incorporated prior to November 1, 2008.

The operator of an MMC Site may republish an MMC contained in the site
under CC-BY-SA on the same site at any time before August 1, 2009,
provided the MMC is eligible for relicensing.


ADDENDUM: How to use this License for your documents

To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and
license notices just after the title page:

    Copyright (c)  YEAR  YOUR NAME.
    Permission is granted to copy, distribute and/or modify this document
    under the terms of the GNU Free Documentation License, Version 1.3
    or any later version published by the Free Software Foundation;
    with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
    A copy of the license is included in the section entitled "GNU
    Free Documentation License".

If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
replace the "with...Texts." line with this:

    with the Invariant Sections being LIST THEIR TITLES, with the
    Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.

If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.

If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License,
to permit their use in free software.
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