BuddyPress.org

You have obviously customised the theme CSS. If you have not changed the HTML or any of the layout CSS, then..

Try disabling all non-BP addons for a test. I see you are running nextgen-gallery (which I have seen cause problems before when attempted to use with BP), piclens, All in one SEO, etc.

If after disabling all those addons (so you only have WPMU+BP running) it still doesn’t work, you could try reverting to the default member theme to see if that works.