Mg expander

![image](https://cloud.githubusercontent.com/assets/2095625/4767794/cf7182b2-5b61-11e4-9fa9-517c30828e3b.png)

We should use `section` or `article` for these. I'd be inclined to say that this should be done a in a separate PR, but we usually just let things like these slip. I suggest we use them for this one, that way we clearly know that we need to fix the others.