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Compass is a stylesheet authoring framework that makes your stylesheets and markup easier to build and maintain. With compass, you write your stylesheets in Sass instead of CSS. Using the power of Sass Mixins and the Compass community, you can apply battle-tested styles from frameworks like Blueprint to your stylesheets instead of your markup. Sass – Sass is part of the Ruby-based project called Haml. It will be installed as a dependency of compass automatically during the next step.