controlling how htmlize fontifies code

[Eric S Fraga <e.fraga@ucl.ac.uk>]

Hello all,

I have to prepare a whole new set of lectures for a new course and I
thought I would play around with =ox-reveal= as an HTML export target
may actually be more appropriate for this course than my usual PDF
target.  And one of the best features of org is that most of the effort
is the same regardless of target so I won't be wasting much time
playing! :-)

In playing around with reveal, I realised that exporting code uses the
=ox-html= exporter (obvious, in hindsight).  This exporter uses emacs's
own fontifying engine to colour code for export.  My problem is that I
use a dark background theme for emacs but want presentations to be based
on a light background.  The code colouring, as a result, is completely
wrong.

Now, I can simply start up emacs with a light background, export my
slides and everything is fine.  However, it would be nice to not have to
start up a new emacs just for this.  Is there an easy way to pretend,
for export to HTML, that emacs is using a light background?  Maybe a way
to advise the exporter?  

Thanks,
eric

PS - ideally, code export to HTML would make use of CSS instead of
     hard-coding in the colours but that's a discussion for another
     day...
-- 
: Eric S Fraga (0xFFFCF67D), Emacs 25.0.50.2, Org release_8.3beta-1303-g3f0398