[CSS] Compass - http://compass-style.org/

Compass is an open-source CSS Authoring Framework.

Why designers love Compass.

1. Experience cleaner markup without presentational classes.
2. It’s chock full of the web’s best reusable patterns.
3. It makes creating sprites a breeze.
4. Compass mixins make CSS3 easy.
5. Create beautiful typographic rhythms.
6. Download and create extensions with ease.

Compass uses Sass.

Sass is an extension of CSS3 which adds nested rules, variables, mixins, selector inheritance, and more. Sass generates well formatted CSS and makes your stylesheets easier to organize and maintain.