Groundwork – A Responsive Front-End Framework
Many web designers now have a favorite front-end framework for developing sites easily.
Groundwork is another good alternative that is built with SASS + Compass and offers an advanced responsive layout.
It has a flexible, fluid and nestable grid system which makes creating any layout possible.
The framework includes many UI components like tabs, buttons, forms, navigation, icons and more.
Groundwork is documented very well and there are templates to get started quickly.