How to change the seperate background div colours within page?

I want to change the background colours of the content area of the page but despite trying various options in the css I haven’t yet hit upon the correct part of the css to achieve what I’m looking for.

Basically I want the main content area to have a black background, with the post and title areas having a white backgrounds.

I’ve illustrated what I have at present (basically the twentyfouteen standard them widened) with a post illustrating what I’m trying to achieve within a post in the page;

http://rocketmonkeypop.co.uk/wptest/