The frame flashes to black between tests on a slower network. It looks better with a light gray background.
Created attachment 232434 [details] Patch
Comment on attachment 232434 [details] Patch rs=me
Comment on attachment 232434 [details] Patch We can't do this. Adding z-index would affect the benchmark.
Also, if we're making change of this sort, we need to bump up the version number. Adding a background color can significantly affect the painting & compositing performance.