I'm pretty sure the idea of managing to separate program logic and presentation for something that needs to output HTML is largely a myth. I've tried, again and again, to do this, but no matter what, you end up with HTML in your program code or program code in the HTML (even if the program code is some templating language, it's still code).

For a really simple app, maybe you could pull it off in some meaningful manner, but for anything even a little bit complex, there's just too many cross-dependencies between presentation and logic.