I haven't checked w/ mozregression, but from the login-item.css log, bug 1597993 seems like the only bug that could have possibly regressed this.

This seems caused by the display: flex; on .container which has been added to make sure the footer gets pushed to the bottom of the page.

Generally, it's not a great idea to use display: flex only to make sure the child takes up the full height (as a side-effect of align-items being stretch by default). height: 100% on .column should be more explicit and self-contained to achieve this effect :)

Once bug 1604140 lands we can simply back out bug 1597993.

[Tracking Requested - why for this release]: UI regression in about:logins, tracking it to avoid forgetting it in case bug 1604140 doesn't land in time in for Nightly 74.

Thanks :ntim, I can make the change in case bug 1604140 doesn't land in time. flex[-grow] rule is missing on .column, unless using simpler height indeed.

Should bug 1597993 be reverted, we probably want to keep focus trap regression test, isolated in its own commit for this purpose.

https://hg.mozilla.org/mozilla-central/rev/eea4b65aa2d1

I have verified this issue and is no longer reproducible on the latest Nightly 75.0a1 (Build ID: 20200211215452). Tested on Windows 10 x64, Mac 10.14 and Arch Linux x64.

• The Login view is wide and the "Edit" and "Remove" buttons are displayed in the left part of the view.

Comment on attachment 9125597 [details]
Bug 1613580 - Restore appropriate width of login view r=ntim,jaws

Beta/Release Uplift Approval Request

• User impact if declined: See comment 0
• Is this code covered by automated tests?: No
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: Yes
• If yes, steps to reproduce:
  • Have at least one login in about:logins
  • Visit about:logins
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Trivial CSS change
• String changes made/needed: None

Comment on attachment 9125597 [details]
Bug 1613580 - Restore appropriate width of login view r=ntim,jaws

Low risk CSS patch verified on Nightly, uplift approved for 74.0b3, thanks.

https://hg.mozilla.org/releases/mozilla-beta/rev/5c21881f00f9

I have verified this issue and is no longer reproducible on the latest Beta 74.0b4 (Build ID: 20200216164042). Tested on Windows 10 x64, Mac 10.14 and Arch Linux x64.

• The Login view is wide and the "Edit" and "Remove" buttons are displayed in the left part of the view.