The color of the header area background, displayed in the part of the header not covered or visible through the images specified in "theme_frame" and "additional_backgrounds".

 "colors": {
    "frame": "red",
    "tab_background_text": "white"
 }

It would be vary helpful if there was a frame setting that could be changed in the extension so I would not have to change it manually upload it an wait for it to be approved just so I can see the change. Currently frame inactive is a option but at least on linux that wont change the inactive tab section color. An it does some weird gnome gtk workaround which at least on non-gnome is vary ugly. Personally In wish the team would use anything but gtk in the future. Frame section: The color of the header area background, displayed in the part of the header not covered or visible through the images specified in "theme_frame" and "additional_backgrounds". See example json "theme": { "colors": { "frame": "red", "tab_background_text": "white" } } https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/theme#colors