Developers are encouraged to follow the Atlassian style guide to ensure a pleasant and uniform user experience. The best (and easiest) way to do this is by using AUI which comes with the same styling as the Atlassian Cloud (default) product. However, the ForgeExtensionContainer comes with a white default background when custom UI is enabled. This will render a white margin around the extension. This is confusing to end users and not at all a nice experience. By modifying the
[data-testid="ForgeExtensionContainer"] container to remove the background we can get a much better user experience with custom UI and AUI. However, this is not possible from within the IFrame (which makes sense for security reasons). Is there a way (or will there be a way) to disable the background or add custom CSS?
Attached screenshot further illustrates the problem: