You are mistaken. It uses the CSS of fashionMArt, but it doesn't use the CSS of your joomla template. This is why you are seeing blue text-link in the TABs. is this is problem you are talking about?
It is because your joomla template's CSS files don't get loaded in the facebox window.
Facebox's page loading is not a special feature that comes with FashionMart, it is already a feature of "joomla". If you type ?tmpl=component parameter to the URL the targeted page will open without the module position (i.e: www.xtremillusion.com/?tmpl=component) . It is called "component" page layout, because it loads only the "component" (it can be com_virtuemart, com_article or anything). We are using this ?tmpl=component parameter to open the product details page inside the facebox, because we don't need the modules and menus, we only need the component, which is the product details page in this case.
To force to load all available CSS files in the facebook (quickLook) window as well, you can include your all available template's CSS files into this PHP file:
- In the above codes, i did it only for template.css and layout.css but there must be other CSS files as well (check your /templates/YOUR_TEMPLATE/css/ folder to see what CSS files there are) you should load all of them to get the exact same look in the original page and the quicklook window.