[bawolff]

Why not? I can imagine a modified abstract css machine which applies the styles to an infinitely long html document. That's much more contrived than the python case, but if we are going to be making arbitrary changes from finite machines, im not sure under what basis we would draw the line.

[maweki]

The html document is potentially infinite, but its finite length is not encoded in the program (css).

One idea is, to have the same program, and if it terminates, it will terminate if you pick a large enough machine. You don't need to "rewrite" the program to use a larger machine.

So in this case the html document is the tape. Potentially infinite, but not in reality. The css program may handle it as infinite.