Chat plugin z-index?

I installed the chat plugin on a MU/BuddyPress site. I'm using the corner box implementation, but I'm having trouble because the box falls behind many of the objects on the page. I'm guessing this has to do with the z-index, but I can't figure out how to fix it.

Currently, it falls behind the image on my front page and behind all of my BuddyPress objects on my BP pages.