I didn't mean that it can be proof to CSS independently of HTML of course. And I suppose this requirement is obvious at least because CSS is not executable with

I didn't mean that it can be proof to CSS independently of HTML of course. And I suppose this requirement is obvious at least because CSS is not executable without HTML at all. Anyway it seems you are quite familiar with the topic, and I believe you heard all the recent buzz around rule110 etc. But a lot of people don't know about this interesting fact yet.