Steps to reproduce

1. Make the window 1024x1024
2. Visit https://ci.blueocean.io/blue/organizations/jenkins/blueocean/activity/
3. Scroll to the bottom of the activity so the header is not visible
4. Click on any run
5. Close the run dialog
6. try to scroll up - you won't be able to!
7. the window location is still set to the run and not the activity