Tweak top bar and search bar styles for small screens.

Closes #853 

![smaller](https://cloud.githubusercontent.com/assets/96776/4211962/7eb72c00-3893-11e4-949a-6e4cd7129d16.png)

![small](https://cloud.githubusercontent.com/assets/96776/4211963/7ed3d8f0-3893-11e4-97eb-c16cfae9411f.png)

![large](https://cloud.githubusercontent.com/assets/96776/4211961/7ea50476-3893-11e4-8d01-90edf5be74d0.png)