@Andrew: I understand what you’re saying. The difference, though, is that the YUI CSS compressor is essentially a string-replacement system, whereas my optimiser actually parses the CSS file. It’d essentially be a complete rewrite. 🙂 That being said, I have looked through the code of the YUI compressor, and I’ve certainly not been shy in realising that I’d missed an edge case or whatever.

There’s still a lot of work to be done on this, but hopefully it’ll become a nice robust CSS minification package over time.