virtuemart category module layout [SOLVED]

[guardiano78]

hello,
i need some help about dropdown in module category.
this is the url: http://ibnet.no-ip.info/joomla3
we have 1 categorY with subcategories: "accessori"
If you click Arrow, you can see the issue.
subcategories are not displayed as in the demo of virtuemart, but they seem to be in a different layer as if it had been set the z-index.
I think the problem is in the css but I can not figure out how to solve.
Can anyone help me?

thanks

[guardiano78]

in my css file i fix height: 32px.
i modified it in min-height: 32px.

thank you all anyway :-)