1973304 - The change of Colours settings to Contrast Control settings removed the possibility to set the default background colour.

Status: UNCONFIRMED

(Firefox :: Settings UI, defect)

Description

[Seff [:seff]]

Steps to reproduce:

• In a Firefox version up to 137 go to Colours settings, set grey as the default background colour and disable the checkbox "use system colours".
• Open a webpage that does not specify a background colour in its attributes or styles. See its grey background.
• Update Firefox to version 138 or later.
• Open the same webpage that does not specify a background colour.

Actual results:

• Webpages without background colour in its attributes or styles are displayed with a white background.
• Since version 138, I cannot set Firefox’s default colours for website backgrounds. The option was removed.
• On webpages that let the background be a user’s choice, it can't be chosen in Firefox any more.

Expected results:

• The webpage should be displayed with the previously set default background colour, grey.
• There should be an option to set a default background colour that only applies to webpages that do not specify a background colour.

Related config:

• browser.display.background_color
• browser.display.use_system_colors
• browser.display.document_color_use

Reference:

• Firefox Release Notes
  138.0 Firefox Release
  April 29, 2025
  https://www.mozilla.org/en-US/firefox/138.0/releasenotes/
  "Changed"
  "Rededicated previous color settings to Contrast Control settings."
• New Contrast Control Settings
  https://blog.monotonous.org/2025/03/06/New-Contrast-Control-Settings/
  "What We Did"
  "In today’s nightly build of Firefox we introduced a simple three-state toggle for color contrast."

Notes on the change:

• What they did solved their problem and caused us another one as a consequence.
• The default background colour setting was available since the beginning of Firefox, since Netscape.
• This change left us only with the alternative to change the background of all pages, rather than just those that don't specify a background colour.

Comment 1

[Seff [:seff]]

Attachment: previous Language and Appearance Settings.png

Comment 2

[Seff [:seff]]

Attachment: previous Colours Settings.png

Comment 3

[Seff [:seff]]

Attachment: current Language and Appearance Settings Automatic.png

Comment 4

[Seff [:seff]]

Attachment: current Language and Appearance Settings Custom.png

Comment 5

[Seff [:seff]]

Attachment: current Colours Settings.png