PostCSS
PostCSS is a tool for transforming styles with JS plugins. These plugins can lint your CSS, support variables and mixins, transpile future CSS syntax, inline images, and more.
PostCSS is used by industry leaders including Wikipedia, Twitter, Alibaba, and JetBrains. The Autoprefixer and Stylelint PostCSS plugins are some of the most popular CSS tools.
PostCSS is built by Evil Martians, an American design and engineering consultancy for developer tools, AI, and cybersecurity startups.
Docs
Read full docs here.