Screenshot with error in the attachment.
Retina, MacOS, Chrome 24.0.1312.56.
I am unable to reproduce this bug on Mac OS X (Mountain Lion) with Chrome 24.0.1312.56 on a 15" Retina MacBook Pro @ 1440x900.
I disabled all plugins for my browser, but nothing has changed.
If I remove border-right in div with class "main" - everything ok.