Steps to reproduce the issue

Go to System > Templates > choose a template > Create Overrides

Expected result

1. All lists have items on a new line
2. Clicking a list item expands it
3. Close button works

Actual result

1. Plugins appear on the same line and are cramped.
2. Clicking them does nothing.
3. Clicking close does nothing (I created an override first so perhaps that causes this particular problem)

System information (as much as possible)

systeminfo-2019-04-28T14_21_07-04_00.txt

Additional comments