Great question.
before you get started you need to figure out a couple of things:
- do you know how css works (specificity)?
- do you know how sass works?
- how modulair do you want to make your new module?
- do you want to lean on atlas or completly replace it.
once you have that figured out, you need to think about the front end methodology,
- do you want to go towards the “seperation of commons” where classes are very semantic?
- do you want to go more towards tailwind where every class explains something about a design element?
- or maybe somewhere in between such as the bootstrap utility class framework?
in order to get started I'd recommend reading this blog:
https://medium.com/p/eed2d0063411
and maybe watch this.
https://www.youtube.com/watch?v=tt1n_yBeJrI&t=1598s
it is for MX8 but the principles still remain strong.