are they CSS stylesheets?
Some devels said that they would start working on new chatwindows based on tkhtml this summer (but I dunno whatever happened to it, and if they have made any progress) and IIRC tkhtml supports css. If so, it will really be a piece of cake. But it's REALLY difficult for the current implementation.
BTW, the link you gave me offers some "omgbandwidthstealer.pn" instead of showing a picture...??
I think it is a png file but somehow it became a typo while moving the file somehow.
Just rename it as a png and it will show you the result i hope.