Okay, just to make sure I'm understanding you correctly, I can put whatever I want in there without doing anything else first? For example, amaury_is_awesome? In your example, I thought "my-style" was being called from somewhere, but I guess not, huh?
Sorry, Brogan. I still don't know all the ropes of XenForo.
I see that EXTRA.css and the custom CSS field both share .userBanner my-style, so it looks like the "my-style" in the custom CSS is being called from EXTRA.css? I'm probably still not understanding, though.
These guys are great and just finished some awesome work for our site that we launch in about 1 week. I am going to a write-up in the next few days. If you are looking for some really good styling @Audentio is without question awesome!