Affected versions

• 75.0, 76.0b7, 77.0a1(2020.04.21)

Affected platforms

• macOS 10.15.3, Windows 10, ubuntu 18.04;

Steps to reproduce

1. Launch Firefox, access about:logins
2. Create multiple logins until scrollbar for available login data is displayed;
3. Hover over the login-user list and scroll up/down;

Expected result

• clean UI;

Actual result

• scroll bar overlaps bottom separator;

Regression range

• First bad: 2019-07-18;
• Last good: 2019-07-17;
• Pushlog: URL
• Potential regressor: not a regression, visible with bug 1560431;

Additional notes

• attached screenshot with the issue visible on macOS and Windows on the right side.

If I understand this bug correctly: This bug describes the faulty behavior where the "create-login-button-container" having a top "border" in which the scrollbar from the "listbox" element overlaps with this "border". Did I describe it correctly? If so, I think a way to fix is to make that use border-top instead of box-shadow (and to tweak the "listbox" list items to not have a bottom border for the final item)? What do you think?

Also tweak style of login-list-item so that there won't be double border at the end of the list

https://hg.mozilla.org/mozilla-central/rev/9ea357870dea

Verified with 81.0b2 on Windows 10,macOS 10.15, Ubuntu 20.