background_color member defines a placeholder background color for the application page to display before its stylesheet is loaded. This value is used by the user agent to draw the background color of a shortcut when the manifest is available before the stylesheet has loaded.
background_color should match the
background-color CSS property in the site’s stylesheet for a smooth transition between launching the web application and loading the site's content.
background_color member is only meant to improve the user experience while the main stylesheet is loading from the network or the storage media; it is not used by the user agent as the
background-color CSS property when the progressive web app stylesheet is available.
|Web App Manifest
The definition of 'background_color' in that specification.
|Working Draft||Initial definition.||Web App Manifest Working Group drafts|
BCD tables only load in the browser