Theme broken on registration page

Hey folks,

Hopefully I can get pointed in the right direction here. Not looking so much for anyone to do the work for me, but an idea of what to do would help. I bought a theme from WooThemes (Therapy), and it breaks on the registration page. The WooThemes guys say they don’t support Multisite mode, which I’m using to cut down on the work of hosting 3-4 sites. You can see the problem here…

http://zatzai.com/wp-signup.php

Anyone have any idea what code, or css or theme file I would have to look at / change to begin to make this work?

…

On a side note, I’ve done a lot of work to make modifications to the theme, and learned a lot about working with child themes in the process. But I’ve had difficulty at times with included files within sub-folders, sometimes I can escape out and include them using the “../../” etc method, and sometimes I can’t. Is there a trick to make this work? Sometimes I am reduced to altering the original file after all which defeats the entire purpose of using a child theme.

I’d ask the WooThemes guys but I’m afraid they’d tell me it’s another matter they don’t support.