320 and up is a 'tiny screen first' boilerplate extension by Andy Clarke.
Susy is a flexible grid-building tool by Eric Meyer, built in Compass/Sass.
This is an example of how one might use them together, to build different grids for different devices on one site.
- There is more code here than is needed. I left most of my default boilerplate styles in place. That could be optimized more, if I cared.