XCart template fix for Firefox

Hey everyone, I need someone who is familiar with CSS, and XCart software to make a header fix for us. After installing a new template and making some changes to it, we've noticed a problem in the cart checkout area, where the header is overlapping some of the data. We've noticed that the first 6 categories when viewing the site in Firefox, you can not click on any of them. I am sure this is just a simple CSS fix, but don't have the time to dig into xCart to find it myself. Please be able to complete this work quickly. The site is [login to view URL] (adult novelties) .. if you view the site in firefox you will know what I mean.