[xwiki-users] xe 2.1 adds a small stripe at the top for some spaces

I all, I've installed xwiki 2.1 right now ... I need some time to become familiar with the new menu structure and the new menu line right above the pages. However I recognized, that spaces having its own title, different from the code, are shown with a small stripe at the top - that's boring (a bit). Kind regards mb