Cleaning up the layout

* adding more space between elements
* improvements on mobiles

I paired with @alicebartlett on this.

Before:
![image](https://cloud.githubusercontent.com/assets/23801/4373167/a4b789e4-432a-11e4-8831-fe66cc1387e0.png)

After:
![image](https://cloud.githubusercontent.com/assets/23801/4373152/7ea9ca28-432a-11e4-8db5-8b15174de8d9.png)