The Default theme may have been a bit too dark. Instead let's have it a
tiny bit lighter (and also foreground color a bit less white).
For now, the old "Default" dark theme doesn't disappear totally and is
moved to a "Darker" theme as we have been discussing and wondering on
whether this is prefered by some people (it is). Aryeom also thought a
darker theme may be a good idea.
Moreover Liam actually thought that losing some of the contrast
(especially with the text a tiny bit less white now) is not desired in
his case where eyes may not be as sharp as they used to. Therefore a
"High Contrast" theme may be needed.
Aryeom also suggested that sliders to choose colors could be a much more
generic solution, which might be possible yet would require more ugly
hacks generating on-the-fly theme changes (we do something similar for
dark theme choice already).
This is all work-in-progress and a result from Wilber Week 2023 work.
