Syntactically Awesome StyleSheets (Sass) is a meta-language on top of CSS that‘s used to describe the style of a document cleanly and structurally, with more power than flat CSS allows. Sass both provides a simpler, more elegant syntax for CSS and implements various features that are useful for creating manageable stylesheets.
Sass Features
Sass can be used in three ways: as a plugin for Ruby on Rails, as a standalone Ruby module, and as a command-line tool. Sass is bundled with Haml, so if the Haml plugin or RubyGem is installed, Sass will already be installed as a plugin or gem, respectively.