Increase max-width on container

Sometimes when I have a lot of new activity the headers end up wrapping into a new line (see screenshot).  Bumping up the max-width a bit helps put them back on one line.

![lots of notifications](https://cloud.githubusercontent.com/assets/95570/3858336/c068fa20-1f0c-11e4-9899-348079f9aca4.png)