Correct font fallbacks

Fonts were incorrect, showing as serif.

Before:

![image](https://cloud.githubusercontent.com/assets/510740/5016132/8d8803b4-6a9b-11e4-9e45-0bf7887b020b.png)

After:

![image](https://cloud.githubusercontent.com/assets/510740/5016145/a76873d6-6a9b-11e4-801b-6487823132c7.png)