I was recently searching for a CSS Framework. Amongst the ones I found that I believe are popular were Blueprint, 960gs, and YUI. I also searched from the Kohana forums since I was planning to use the CSS framework on trying out Kohana and found BlueTrip. Looked really nice and was quite easy to use (check out its documentation :D) although I haven't much explored it.
BlueTrip's definition taken directly from its site:
A full featured and beautiful CSS framework which originally combined the best of Blueprint, Tripoli (hence the name), Hartija, 960.gs, and Elements, but has now found a life of its own.
And its Feature List:
- 24-column grid
- Sensible typography styles
- Clean form styles
- A print stylesheet
- An empty starter stylesheet
- Sexy buttons
- Status message styles
Nice! 8)