Sets the background color for the badge. Tabs without a specific badge background color will inherit the global badge background color, which defaults to [217, 0, 0, 255]
in Firefox.
From Firefox 63, unless the badge text color is explicitly set using browserAction.setBadgeTextColor()
, then the badge text color will be automatically set to black or white so as to maximize contrast with the specified badge background color. For example, if you set the badge background color to white, the default badge text color will be set to black, and vice versa.
Other browsers always use a white text color, so setting a dark background may be preferable to ensure the text is readable.