Add option to select main color?

[hagenw]

One first step to tackle #5 could be to add the option to select the main color of the theme.
This seems to me the most important one (maybe folks that use a dark theme disagree with me), as you then can make the theme match the color of your already existing HTML pages or whatever you would like to match.

Looking at the current implementation we use the following colored elements where the color conveys a meaning:

And we have the following colored elements where the color does not convey a meaning:

And some gray elements, that I would not count under colored:

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So, the default color of the theme seems to be blue as this is used for links and some boxes.
We could make this changeable, but I guess you selected the blue in a way that it matches the red parts of the theme, which shouldn't change its color as the color conveys meaning.

[mgeier]

I think we should introduce CSS variables for all colors as part of #5.
Then we can have two sets of definitions, one for the light theme and one for the dark.
We just have to come up with meaningful names (probably with a custom prefix).

I've collected a few links in #5, maybe some of them can serve as inspiration?

BTW, there is yet another color: https://insipid-sphinx-theme.readthedocs.io/en/0.2.7/showcase/admonitions.html#topic