SASS.

Sass is a CSS extension that gives power and elegance to this simple language. Sass will give you the ability to use variables, nested rules, mixins, inline imports, and more, all with a fully CSS-compatible syntax. Sass helps keep huge style sheets well organized and make small styles work faster. Sass can be used in three ways: as a command line, as a separate Ruby module, and as a plug-in for a rack framework, including Ruby on Rails and Merb.