Fix the search box height

Maybe I'm the only one to see this, but the search box has an hardcoded CSS height that makes its content unreadable on my browser (Chrome 38 / Mac). See attached screenshots, before and after the patch.

Before :
![unreadable-searchbox](https://cloud.githubusercontent.com/assets/516479/5071410/d419b56a-6e70-11e4-8eb3-7e6e91ac3aa4.png)

After :
![correct-searchbox](https://cloud.githubusercontent.com/assets/516479/5071411/d794a092-6e70-11e4-8e47-81bac695d537.png)