The most used css library now is sass ( scss syntax )
Quasar should support it
No. Stylus is like SASS on steroids. You can write SASS in Stylus and it will work
You can use whatever CSS preprocessor you like. All you need is to add the right webpack loader for it. More info in documentation (Guide).
But that makes it impossible for SASS to access Stylus variables right?
You can't have your cake and eat it too. If you know Sass well, it should be very easy for you to learn Stylus. It's better than Sass for a number of reasons.
Scott
@MatanYed
It is a lot of work and out of scope for this project to have a SASS port and LESS port and whatnot 馃榿
But if I understand correctly, you're thinking about Bootstrap having less and sass versions, so that you can easily theme Bootstrap using your favorite CSS preprocessor and tweak those branding colors and sizes, etc. Note that bootstrap also has some unofficial port of Bootstrap to Stylus.
The most logical approach would be to also use Stylus. Keeping a some-variables.scss file and a some-variables.styl file in sync is not pretty.