pyScss compiles Scss (Sass), a superset of CSS that is more powerful, elegant and easier to maintain than plain-vanilla CSS. The library acts as a CSS source code preprocesor which allows you to use variables, nested rules, mixins, and have inheritance of rules, all with a CSS-compatible syntax which the preprocessor then compiles to standard CSS.
Scss, as an extension of CSS, helps keep large stylesheets well-organized. It borrows concepts and functionality from projects such as OOCSS and other similar frameworks like as Sass. It’s build on top of the original PHP xCSS codebase structure but it’s been completely rewritten, many bugs have been fixed and it has been extensively extended to support almost the full range of Sass’ Scss syntax and functionality.