This is very pretty, but I've never met a modal dialogue box on the web that wasn't incredibly irritating and could have been done better in the interface itself.
Definitely an improvement over the standard, and looks like it should degrade gracefully on old browsers. I can't help but wonder if fixed/absolute elements might not break the illusion, so beware. But still, (yet another) nice job from Hakim!
On my old Thinkpad X200 with Ubuntu/Intel graphics.
Firefox 14. Smooth transition lasting about 1 second. The smoothness suggests more than 4fps. The text within the modal window 'jitters' or 'shuffles' slightly after the transition has completed, as if it is kerning or loading a font.
Chrome 21 (stable for Ubuntu/Debian) much less smooth, quite jerky. The font 'jitter' isn't there.
I thought this was really cool, but couldn't find a repo for this anywhere. Instead of relying on his demo to exist forever, I've moved all his code(minus analytics and sharing) into a github repo here: https://github.com/jonpaul/avgrund-demo
Agreed, really cool concept, but a bit slow. I like where his head is at, though, very cool.