Code highlighting block has extra background color visible behind rounded corners

DIV.highlight is defined in pygments.css, but Boostrap also defines
background for PRE
The problem is obvious in case of
pre { border-radius: 140px; } or when code block has an sidebar like in
http://dyna.readthedocs.org/en/latest/tutorial/dijkstra/
Merge pull request #59 from kosiakk/master

Code highlighting block - background color visible behind rounding