I feel dumb for being stuck already, but here's the situation:

http://www.tweakdperformance.com/onlinestore/

As you can see, only a small portion of the logo is visible. I've played around with:

includes/languages/english/RI_TEMPLATE_07/header.php

and

includes/templates/custom/css/stylesheet.css

But I can't seem to correct the problem. Suggestions?