The control buttons may not be displayed

[yoshihiro503]

Severity

occurs occasionally

Steps to Reproduce

1. open with a gist code
2. click the power button
3. reload the page

The control buttons does not appear.

Environment

environment
OS	Mac OS X 10.15.5 (Catalina)
CPU	2.3 GHz Intel Core i7 Quad Core
RAM	32 GB 3733 MHz LPDDR4
Browser	Firefox 89.0.2 (64 bit)