Pure – A CSS Framework By Yahoo!
It is so good to see new and quality frameworks are being introduced regularly by the web design/development community.
The framework is built with responsive layouts in mind and has styles for typography, grids, forms, buttons, tables and navigation.
Markup used is very simple and the whole framework is pretty lightweight (5.7KB minified and gzipped).
Also, it is modular and styles for each module can be used separately.