Reduced size of mobile nav to not collide with content

# Before
![screen shot 2013-09-22 at 18 56 41](https://f.cloud.github.com/assets/2061937/1188892/a60af8a0-23f3-11e3-9bf8-d641ae5dbc8c.png)

# After
![screen shot 2013-09-22 at 18 56 58](https://f.cloud.github.com/assets/2061937/1188890/a2b9ae8a-23f3-11e3-86c7-1cf89b92ba7d.png)