Moving away from SASS

[ulgens]

While working on #2212, I encountered an issue: libsass package was requiring build dependencies, even though its readme states that

Provides prebuilt wheel binaries for Linux, Windows, and Mac.

A further investigation revealed that this is an issue with M-series processors: #2248 (comment)

While looking further, I found out that libsass itself is deprecated:

Warning: LibSass is deprecated. While it will continue to receive maintenance releases indefinitely, there are no plans to add additional features or compatibility with any new CSS or Sass features. Projects that still use it should move onto Dart Sass.

At this point, it was clear that at some point we will need to move away from using libsass. During the related discussions, @bmispelon stated that moving away from SASS is also an option:

...maybe abandon sass altogether and use modern plain css (I wonder what feature of sass we actually need that wouldn't be standard css nowadays)

So far, me, @pauloxnet and @adamzap are supportive of this idea.

I'm creating this issue so we can discuss anything related to the idea of moving away from SASS and the related implementation.