Alternate mobile styling

This adds an easier-to-read mobile styling for the website.
Previously, this is what you would see on a smaller screen:
![screenshot 2014-10-15 21 14 57](https://cloud.githubusercontent.com/assets/2782749/4656221/e2d58722-54d1-11e4-9d1a-760928b645a0.png)
Now, you see this:
![screenshot 2014-10-15 21 15 37](https://cloud.githubusercontent.com/assets/2782749/4656226/f690aa4e-54d1-11e4-8ed3-5b934e605f3f.png)