A few quick searches discovered that I'm obviously [not the](http://morethanseven.net/2008/10/13/unit-testing-css-looking-solution/) [first person](http://www.thoughtballoon.co.uk/blog/2008/11/11/example-css-style-guide-unit-testing-for-css) to have the thought **"Can I unit test my CSS?"**. 

I'm wondering if anyone here has taken on CSS Unit Testing successfully? If you've tried and failed, or just have your own theories, please tell me why it (apparently) hasn't been done yet?