Steps to reproduce:
Affected sites include arstechnica.com, bitchute.com and extremetech.com. There are many others but those are the ones that I have tried recently.
EDIT: Fixed bogus link.
Just to add that I am testing with a mouse, though the use of a trackpad should not make any difference.
Is https://www.waterfoxproject.org/blog/ similarly affected?
I might test with a Mac later.
The waterfoxproject.org site is unaffected by this issue.
Thanks … double-checking: just that one page in particular (not the site in general), because it featured in another issue …
Indeed, the blog page is unaffected.
Not limited to Waterfox.
… Affected sites include arstechnica.com, bitchute.com and extremetech.com. …
I can't connect to the third, but the first two are bugged in Firefox ESR 52.7.2 (64-bit) on pre-release build 17E190a of Mac OS X 10.13.4.
Also bugged:
Is there a plan to make the site work with Firefox ESR 52.x?
– there's not.
Given the incompatibility with sites such as Ars Technica, we might find something in Bugzilla@Mozilla.
Upstream bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1408701.
Mozilla bug 1408701 - Firefox scrollbar has no thumb on some pages (on macOS 10.13?)
RESOLVED FIXED in Firefox 57
https://hg.mozilla.org/releases/mozilla-beta/rev/adc0384c565a
Bug 1408701 - Ensure that we continue to show dark scrollbar thumbs on macOS 10.13 when scrollbars are always displayed. r=mstange, a=ritu
Ha! You beat me to it 😄