Cap the byline width on interactive pieces

Fix for:
![screen shot 2014-12-09 at 17 39 34](https://cloud.githubusercontent.com/assets/2236852/5362382/691a2284-7fca-11e4-9fcc-f919d48d08b9.png)

Now looks like:
![screen shot 2014-12-09 at 17 39 26](https://cloud.githubusercontent.com/assets/2236852/5362391/709696dc-7fca-11e4-9fb0-11ef31d913e3.png)