[Bug]: Overlay/floating scrollbar not working?

[MaxHasBeenUsed]

Pre-Submission Checklist

• [X] I have checked the existing/closed issues to ensure this issue has not already been reported.
• [X] I am using the latest supported version of the browser.
• [X] I have tried disabling all browser extensions/add-ons to rule out interference from these.
• [X] I have tried clearing the browser cache and cookies.
• [X] I have checked with a new profile and the issue still occurs.
• [X] I have provided detailed step-by-step instructions on how to reproduce the issue.
• [X] I have included relevant screenshots or console outputs.
• [X] I have checked that this problem is not occurring in the latest version of Firefox ESR.
• [X] This issue is specific to this browser and does not occur in other browsers.

Bug Summary

'overlay-scrollbar' is set to true, but the scrollbar is still taking up a separate space.

Reproduction Steps

0. Disable userChrome.css
1. Enable 'widget.windows.overlay-scrollbars.enabled' in about:config
2. Enable 'widget.gtk.overlay-scrollbars.enabled' in about:config

Expected Behavior

Scrollbar be floating on webpage.

Actual Behavior

Scrollbar is still taking up space.

Screenshots

Browser Version

11.17.8

Operating System

Windows 10 19045.4780

Additional Context

No response

[MaxHasBeenUsed]

The issue has gone for me for now, but I don't exactly know why. Possible relative info:

• Floorp updated to 11.18.1
• Changed from "Firefox Proton · Lepton UI" to "Firefox Proton UI" in Floorp settings. But changing back to "Lepton UI" and trying all custom settings for it didn't reproduce the issue.

Nevertheless, I think this issue is okay to be closed now. Reopen if needed.