Looking over your HTML, class .logo is responsible for behavior of that container.
<div class="logo">
<a href="http://ntphealthproducts.com.au/cart/home.php">
<img src="/cart/skin/common_files/images/xlogo.gif" alt=""/>
Try in Firebug to delete class="logo" and X-Cart logo will be visible. But thanks to css "display: none" for (.logo img) it won't appear in Frontend.
So, class .logo is creating you trouble because you modified it wrong.