Created attachment 366888 [details] video I'm seeing very dark background color when I hover over some tweets on https://twitter.com/geekylonglegs/status/1111806913069674496 Not sure what the hell is happening here but it looks awful. Maybe it's a page issue?
I can reproduce this. Oddly only around that video. Looks like some kind of corruption.
Does it reproduce with "full-page accelerated drawing" disabled?
Created attachment 367495 [details] Video
Looks like Cmd+F with "All caps?" would make it more likely to reproduce. I can reproduce on STP79 as well as Safari 12.1.
<rdar://problem/49944159>
This appeared to be fixed now.