Interesting approach. There are many many factors with styling in Tiki and if you can develop a style that moves away from the typical 3 column layout you are cured for example http://www.damosoft.co.uk
There is also the LeftColBug which affects Mozilla and is known to be an actual bug inthe browser itself. I've been running 1.7 for a while now and it seems to be fixed.
Maybe Luciash might comment more. He runs KDE and also the KDE wiki using TikiWiki.
Certainly tho, not all styles are compatible with all browsers, that is a known Tiki fact. Moreneat is about the best developed style, so if you want to create your own theme, copy moreneat css and templates as use them as your base.