Links and icons in user setting popup are not visible

Hi,
I have strange issue on my EasyDiscuss forum. If you open the user settings popup on forum frontend, there are no links visible inside. There should be "My profile", "Edit Profile", "My Favourites" and "My Subscriptions" links in popup window, but the links and icons are not visible. If I look at the source code, the links are there, just not visible. I guess it's some CSS issue, but I can't find it.

thanks for your help
Aleksander