Re: Changing BP Admin Bar to Fluid Width in BuddyPress Default Theme
than the admin bar is controlled by lines #17-35 in adminbar.css. The width is set to appear 100% of what is available, and in the case of the default theme – the body is set to 960px and max of 1250px. if your child theme also has the #bp-default css ID for <body> than lines #25-32 of adminbar.css also apply. trial and error is the way to go. 
