Most of the basic stuff (like background colours, font-families, etc) is pretty well supported from my experience -- certainly all the current styling could be done with CSS to support NS4+, IE3+, Opera and Gecko based browsers.

Of course, once the classes are in there, if users want to override this and use some of the more obscure constructs to change the general appearance. It'd also mean that I could fix my current alignment problem :)

By the way, I believe the alignment issue to be due to IE6 inheriting styles from parent nodes correctly - a bug in previous versions meant it didn't do this -- either that or it's being dumb(er than normal)...

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RatArsed