2076676 - Sidebar appearance is inconsistent with non-default themes when “Expand sidebar on hover” is enabled

Status: NEW

(Firefox :: Theme, defect)

Description

[Simona Badau, Desktop Test Engineering]

Found in

• Firefox 158.0b1

Affected versions

• Nightly 159.0a1
• Firefox 158.0b1

Tested platforms

• Affected platforms: Windows 11 x64, macOS 26, Ubuntu 24.04

Preconditions

• Ensure Vertical Tabs are enabled
• In Customize sidebar -> check Expand sidebar on hover.
• Ensure at lease one selectable profile is created.

Steps to reproduce

1. Navigate to about:editprofile.
2. Change themes and hover the mouse over the Sidebar.
3. Observe the Sidebar while it expands.

Expected result

• The Sidebar color with non-default themes selected should match the main chrome and have rounded corners, as it does when the Default theme is selected.

Actual result

• With the Ash and Smoke themes in Light mode, the Sidebar is darker when Expand sidebar on hover is enabled than when it is disabled.
• The Sidebar corners are not rounded when non-default themes are enabled - this is more noticeable in Dark mode.
• The Sidebar corners are also not rounded with the Default theme when the window is inactive.
• Please see the screen recording for more details.

Regression range

• The issue was introduced with the Nova styling changes.

Additional notes

• This is logged as a follow up to Bug 2070550.

Comment 1

[BugBot [:suhaib / :marco]]

The severity field is not set for this bug.
:hjones, could you have a look please?

For more information, please visit BugBot documentation.