Header cleanup

This should make the headers look a little better on small screens (like the iPhone) and prevent the issue where the navigation was adding a smaller scroll bar (making scrolling down a bit more difficult on touch screens).

I also made the search box on the home page a little smaller, which prevents it from getting squished against the right side too early as the browser gets smaller.

As you can see in the screenshots there's still work to do with wrapping text, but pending the addition of a hamburger menu or something to collapse the menu on small screens, I think this is an ok solution.
![2014-06-15-145756_308x1079_scrot](https://cloud.githubusercontent.com/assets/666493/3281861/93a864ae-f4c7-11e3-9b1f-6750e065510b.png)
![2014-06-15-145808_308x1079_scrot](https://cloud.githubusercontent.com/assets/666493/3281862/96267694-f4c7-11e3-87ee-ff973ae70603.png)