I don't know, since I haven't looked close enough at the AWeb sources yet. However, CSS is a typical feature that might be very hard to bolt onto an existing design unless the current design is *very* extensible (which it doesn't seem to be). I don't think it would be possible without a serious redesign of AWebs architecture...
Although I could ofcourse start, but it would be hard for me to promise anything usable in a month. The most simple CSS properties would be quite easy to implement (like text color etc), but implementing *everything* would probably be quite hard...