It's already bad enough that HTML/CSS barely works in the target web browser environment, I don't see why anyone decided it was a good idea to use it for books.

I've often thought about figuring out a subset that operates fast on any computer and sticking to that for any web pages I make. If someone figured that out for epub, it would make it much, much more useful.

Ah, yes. When I paint, I also leave the middle unpainted, in case some people have a crack in their glasses that would make the painting look weird. Or maybe we should tell glasses makers to make better glasses and let the artists make their art.