Fix 30px of blank space when there is no banner in the header.

When there is no banner set, there will be 30px of blank space in the header (as opposed to being flush to the top, like in OA 2.13):

![selection_019](https://f.cloud.github.com/assets/191561/2278244/20ac85b0-9f50-11e3-8fb2-4590fbb7d524.png)

This PR will fix it!

Random note: the environment is set to ":development" so this also changes a whole bunch of line numbers in the screen.css. There would be less noise in patches/PRs if this were set to ":production" - but I didn't change it here since that's not related and I'm not sure if maybe you want it this way until releases or something like. But I thought I'd point it out anyway. :-)