The YUI Compressor is also able to safely compress CSS files. The decision on which compressor is being used is made on the file extension (js or css).
Several GUI’s are available :
- Smaller (for Mac)
- yuicompressorgui (for Windows)
- Easy YUI Compressor (for Windows)
Online versions are available at the website of Zileex Media, of Rodolphe Stoclin and of gpbmike.