Sharegroup Customization

I need to edit the look and feel of my Sharegroup galleries, but it appears that this may not be possible. The logged-in menu bar changes for sharegroups, which inhibits me from making it look different. Is there any way to customize the look of sharegroups? To be more specific, this is the one I'm trying to change: www.mattpilsner.com/share/Nelsons . I'd like to change the size of the tiles and get rid of the "Share these photos:..." link in the description.