Gridless: HTML5-CSS3 Framework For Responsive Websites
Gridless is a boilerplate for creating responsive and cross-browser/platform websites with beautiful typography.
It doesn't come with any grid systems, rather, the focus is on progressive enhancement and being a starting point for any project (which you can add a grid system later).
The framework has rules for CSS normalization (no CSS resets), print styles for optimized performance, an optimal caching and a well-organized folder structure that you may feel comfortable with.
Gridless works on all major browsers including IE6.