slack.com - see bug description

[miketaylr]

URL: https://slack.com

Browser / Version: Firefox 61.0
Operating System: Linux
Tested Another Browser: Yes

Problem type: Something else
Description: Scrolling over a large message in Slack will unhighlight the message during scrolling and rehighlight it when scrolling stops, which causes a flickering-like effect. In Chrome, the message is continuously highlighted during scrolling.
Steps to Reproduce:
All I've done is scroll.

From webcompat.com with ❤️

[suprith4989]

Thank you for the report. I am not able to reproduce the issue using Firefox 62, on Fedora 28, x86_64 arch. All I've done is scroll in multiple slack channels that I've joined using my login which have large messages. Not sure if this issue is specific to Firefox 61.0.

Please comment if I should do something differently.