Chrome Version: Chromium 73.0.3631.0

What steps will reproduce the problem?
(1) Go to http://dl3.webmfiles.org/big-buck-bunny_trailer.webm
(2) Request Picture-in-Picture
(3) Play video until the end
(4) Picture-in-Picture window is white (because last video frame is white)

What is the expected result?
I should be able to find the close button to close the Picture-in-Picture window.

What happens instead?
I can't find the close button because it is white. The only way to find it is to hover the close button.