CSS Template For Responsive Layouts – xyCSS
xyCSS is a simplistic and lightweight CSS framework (with a single CSS file) for building responsive and liquid layouts.
It includes styles for the structure + typography and focuses on clean, semantic markup.
The CSS reset used is the popular one from Eric Meyer. It is ready to support any device with any resolution and there is a detailed documentation with demos.
Also, it has a wide-range of tools for working easier including jQuery plugins for displaying a grid in the background or changing the srceen width, xyCSS-compatible WP plugins and more.