Rider, I have the same problem and I thought it was due to previously installed iTT-specific tweaks. But I just searched and I don't have any. OTOH, I do set my min font size to 20, like you. So you're right, it's a problem. And one that didn't arise on the old iTT and that I don't recall running into elsewhere.

Edit (5-8-09): Hmm. I think I was mistaken. Even with no special .css and the min font size even at 12, I get screwed up maemo.org Talk formatting like Rider shows above. It may be something I did to prefs.js.