Doc Tab Not Fully Closed on FF

[sganz]

Describe the bug
A clear and concise description of what the bug is.
When using Firefox and opening and closing the Doc's panel it doesn't fully close. Leaving the panel partially open.
To Reproduce
Steps to reproduce the behavior:
Use Firefox, open/close the docs for a valid endpoint

Expected behavior
Doc's panel should be non-visible

Screenshots
Attached

Desktop (please complete the following information):
Windows 10 Home
Firefox 61.0.1 (64 Bit)
Altair - v1.7.6