Facebook Like button conflicts with drop-down navigation

Hi everyone,

I have a dropdown navigation on my site that conflicts with the Facebook Like button in my right sidebar.

The problem appears when the sub menu expands – it is supposed to overlap the Like button, but instead, the Like button shows through the submenu making the items unclickable.
How do I force the menu to be on top?

The problem can be seen here: https://www.bageglad.dk

Any help is much appreciated!