This example, while nifty, doesn't show that HTML+CSS is Turing complete, because the user still has to provide the looping. That's like saying that my compute

This example, while nifty, doesn't show that HTML+CSS is Turing complete, because the user still has to provide the looping. That's like saying that my computer isn't a Turing machine (modulo finiteness of memory) because I need to plug it into a socket to run it. Turing machines are a very abstract notion of computation (and one of the most general ones we know of), and a lot of things can be used to simulate one. Turns out HTML+CSS3 is yet another such thing.