Lars Ingebrigtsen <larsi@gnus.org> writes:

> Yes, I think we should work towards using proportional fonts throughout
> Emacs (where it makes sense) in the Emacs 29 cycle to get a more
> consistent and modern look.  For instance, "emacs -Q" uses proportional
> fonts in the menus and the toolbars (on most systems), but not in the
> mode line or the header lines.

So here's some low-hanging fruit: the header-line and breadcrumb in info.

I'm not sure if the header-line should perhaps just default to use a
proportional font though?  In tabulated-list-mode, we use :align-to so
there is nothing there that would immediately break.  And any place
where we don't use :align-to, we should perhaps just fix in any case.
I'm not sure, which is why I am asking.