Groundwork is a fully responsive HTML5, CSS and Javascript toolkit. Using Groundwork, you can quickly build web apps that work on virtually any device. Groundwork has been built from the ground up with the incredibly powerful CSS preprocessor, Sass.

Featuring an incredibly flexible, nestable, fluid grid system: the Groundwork grid system supports any columns in any fractional amount from halves to twelths. Groundwork is open-source, hosted on Github and 100% free.

Requirements: Sass & Compass
Demo: http://groundwork.sidereel.com/
License: MIT License