Fixed footer nav width for small screens

Before: 

![screenshot 2014-12-17 23 12 55](https://cloud.githubusercontent.com/assets/1451471/5479975/6bfae258-8642-11e4-88fa-4cdb330d930e.png)

After:

![screenshot 2014-12-17 23 13 10](https://cloud.githubusercontent.com/assets/1451471/5479979/7565b764-8642-11e4-8829-f4051e46037b.png)