Changing style for unregistered users

[DiscussAnything]

I made a new style/template set which I want to use for unregistered users. It's very limited in options, so people may be more willing to sign up.

Anyway, I can't figure out how to change the colorstyle for unregistered users. I searched through the templates and it doesn't appear to be in there. The php files are too complex for me to quickly go through.
It seems to have something to do with the styleid, and that unregistered users somehow always use style id 1. Renaming the style from Default to something else, and making the new style Default doesn't do anything.

Can anyone tell me what I need to change where? It's probably not all that big a problem, but I can't seem to figure it out.

thanks a lot in advance