Make static error pages responsive

Let’s show mobiles some love.

## Before
![before](https://f.cloud.github.com/assets/436043/1340264/326a3b72-3627-11e3-9fba-3a6ba3a33256.png)

## After
![after](https://f.cloud.github.com/assets/436043/1340265/38b60bb4-3627-11e3-9ccf-de5ec4c6dc64.png)