right sidebar buddy members/ groups widget problem

Hello,

I am using the MesoColumn theme and I tried to put the buddypress-group- widget on the right side bar, which itself is working perfectly fine. Unfortunately the heading of the widget is blocking/overlaying the area where the user is supposed to choose what kind of group he is looking for (new, active., etc.) You can see the problem here http://willkommenshilfe.de/social/test/
The same thing occurs when using the buddypress-member-widget.

How can this problem be solved?