Layout Issues in Firefox

Hello!
I bought Grid View Pro but experience some CSS-Issues with Firefox.

Could you have a look at http://www.didactmedia.eu/wordpress/?page_id=18 ? The boxes for the variants (Produktoptionen) does not align with it’s parent. How do I fix this?

It works fine in Chrome.

Thank you for your answer!

http://ww.wp.xz.cn/extend/plugins/wp-e-commerce-grid-view/