I've copy-pasted the example directly from the manual: http://xenforo.com/community/resources/creating-custom-user-group-banner-css.2000/
Nada. I end up with a white, transparent banner with black text. In fact it seems to ignore whatever colors I enter entirely. If I remove the .userBanner part it just dumps to plain black text in that spot. So it's seeing something, but it's like it's ignoring all the parameters.