Header Image on Blog Posts fixed

Got an issue with the layout.

The default background image works perfectly, stretches across the screen.

When you set a header image on individual posts it ‘cuts’ off and doesn’t stretch at all to cover the background.

http://velocityeugaming.com/guild-wars-2-updates/

At the very least being able to choose a background colour would be useful if it’s just for header type images.

Thanks for your help in advance.