Sioyek features an option to set the background color for normal
operations (`background_color`) and for custom color mode
(`custom_color_mode_empty_background_color`) separately since this
commit:
0c2251b1be
Here, we change flavours to *only* target the custom color mode, leaving
the normal background color as it is.
This will not work yet for the current official sioyek 2.0 release which
is still the release for archlinux as of 2023-10-16, but it will already
work for its git release. Should work for everything as of the next
official sioyek release.
Switching from my custom, brittle, styling implementation `styler` to
the wonder `flavours` program which does exactly the same only with more
clarity, faster and - I would presume - more stable.
