CSS compression with own PHP class VS CSSTidy
It makes sense to optimize the site’s cascading style sheets (CSS), as it pages load faster, and it reduce the amount of data transferred, and just combining css files could significantly reduce requests to server. So users benefit from faster page loads and webmaster of the sites benefits from the cheaper price of the transferred data.
I have used CSSTidy on many projects. And CSSTidy is very good tool for packing CSS and it can even fix CSS errors.