Just build a new theme with zen. It all went smooth. But being more a techy then a designer I only tested with FireFox, Gnome Web Browser (Gecko 1.8), Opera, Safari and forgot IE 6 which I have through ie4linux. Guess what ... it broke with IE 6.
Yes I know ... IE is out there for real so you better test. But it is a drag for sure. The designer uses IE 7 where it looks ok. So maybe in the near future we are saved a drag or two :-)
- IE is out there: http://www.w3schools.com/browsers/browsers_stats.asp