CSS that tries to be a declarative approach to describing behavior. This is wrong in my opinion like HTML tags for styling were wrong. I think this is wrong because behavior is so incredibly complex that you end up defining rules for everything - and in the end, using a imperative language is much simpler.

I know it's different, but the argument here http://dealloc.me/2011/06/24/d3-is-not-a-graphing-library.ht... applies in a similar way.