I'm seeing css / layout issues with the timeline overview

The frames overview svg is laying out too high:

<img width="975" alt="screen shot 2018-10-01 at 11 05 34 am" src="https://user-images.githubusercontent.com/1269969/46306754-fe17a300-c569-11e8-8243-ca8d2c0a7469.png">
