/a>, <a href="http://lesscss.org/">Less</a> <a href="https://github.com/postcss/postcss">PostCSS</a> and others that give languages new capabilities. Once you've learned how to work with CSS variables, you'll never go back to plain CSS. In the same way, the ability to work with functions (mixins) and extends makes your code smarter by allowing you to create reusable bits of code. Today some of these libraries, like Sass have been ported over to JavaScript for blazing performance and without requiring a Ruby