Co-op form radio buttons render improperly on mobile

In Chrome 68 for Android, scrolling down on the co-op form causes the radio buttons to shift improperly:

![screenshot_20180825-142226](https://user-images.githubusercontent.com/1261595/44623792-b5076b80-a8a6-11e8-975f-bb575f4b6172.png)
![screenshot_20180825-142230](https://user-images.githubusercontent.com/1261595/44623791-b5076b80-a8a6-11e8-9c00-8e482e570b3f.png)
