Use scss instead of plain css

[Paradyx]

Use scss magic to clean up code and make it more maintainable. Suggested by @Tikrass

[sudo42]

Hugo is able to process SCSS, but it seems to be meant for themes.
This would match my plan to move the "theme-componets" (which we are just overriding/shadowing at the moment) to a separate theme (+ repo?).

[Paradyx]

The theme will only be used with hugo. No need for an extra repository for now.

[sudo42]

True. But at least we could create a "local fork" of the current base theme inside of this repository instead of the current (rather unsatisfying) solution.