sass4

https://github.com/VladimirIvanin/ruby-sass

This is a fork of Ruby Sass with modern Ruby compatibility (Ruby 3.0+). Original Ruby Sass is deprecated! See https://github.com/sass/ruby-sass for details. Sass makes CSS fun again. Sass is an extension of CSS, adding nested rules, variables, mixins, selector inheritance, and more. It's translated to well-formatted, standard CSS using the command line tool or a web-framework plugin.