Crystal: Crystal docs dark theme

[j8r]

Some developers likes dark theme - more gentle on the eyes when codding at night :smile:

The CSS media prefers-color-scheme can be used for auto-detection o the light/dark theme user preference

The prefers-color-scheme CSS media feature is used to detect if the user has requested the system use a light or dark color theme.

Other similar tools supporting it:

• https://devdocs.io
• https://doc.rust-lang.org/std/index.html

[straight-shoota]

Sure, sounds good enough to me.

But I would actually hold off on such non-essential features to the doc generator until we do a bigger refactor of the internal implementation. That will subsequently also make it easier to iterate on frontend features.

[Blacksmoke16]

Custom Properties could also be a cool future addition. It would abstract the coloring of things to a single CSS file that could be overridden to allow for custom styling.