fix color for background below footer

Incorrect bg color:
![testing_with_karma___ember_app_kit](https://f.cloud.github.com/assets/514063/1180352/f82210dc-21f1-11e3-842b-675778ef24c0.png)

Correct bg color:
![testing_with_karma___ember_app_kit](https://f.cloud.github.com/assets/514063/1180354/03b06c64-21f2-11e3-92c1-9edc8853335b.png)

You only see this issue on pages that do not stretch full length, such as testing.html that has not had content filled in yet.