cool, but the fact that you can now do this with CSS is part of the reason that a new browser engine is so unlikely - one of 100000 things that css can do now and need to be supported :(

Maybe we should have kept CSS simple and JS optional. Maybe we took a few wrong turns...

It's all additive so each new feature does indeed add complexity, but my impression is that it's often the older features and all their quirks which are the most difficult to implement. Adding a few math functions is much easier than ensuring compatibility with CSS2 floats.