The color of selection in the comments is indistinguishable from preformated text in Firfox

Issue Summary

While default color of the text selection in Chrome, Edge and Safari is blue in Firefox the default color of the text selection is gray. The color of this gray on some platfrom are almost identical match for the pre-formatted text background of the pull request and diff comments.

Windows, Linux, MacOS
Firefox 83.0

Steps to Reproduce

Windows, Linux, MacOS
Firefox 83.0

1. Open any pull request
2. In activity add a comment OR go to Diff view and create new comment
3. Enter some preformatted text with hotkey "`"
4. Select the text inside the preformatted text space.

Expected Results

The text selected with a different contrast color like in Chrome:

Actual Results

The selection is barely visible in MacOS

The selection is completely invisible in Windows 10

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available