Per http://bedrock.readthedocs.org/en/latest/tabzilla.html#requirements

    Background images must not be attached to the <body> element.

Background was attached to <html>, now #outer-wrapper

    An element other than the <body> should add a 2 pixel white border to the top of the page (border-top: 2px solid #fff;)

The 2px border was added by <body>, now #outer-wrapper