Add example text on large screens to help with inputting keys and media queries

Closes #257

## Large Screen Screenshot

![](http://f.cl.ly/items/2Z3l2V472N3C2r2k1Y3U/Screen%20Shot%202014-05-27%20at%2012.19.23%20PM.png)

## Small Screen Screenshot

![](http://f.cl.ly/items/372G1W3N103v111D0e1C/Screen%20Shot%202014-05-27%20at%2012.19.34%20PM.png)