background.html

<!DOCTYPE html>
<!--
Workaround for including background page as a module script, see https://bugzilla.mozilla.org/show_bug.cgi?id=1394303.
See also https://discourse.mozilla.org/t/using-es6-modules-in-background-scripts/29911/3
-->
<html lang="en">

<head>
	<meta charset="utf-8">
	<script src="browser-polyfill.js" type="module"></script>
	<!-- <script src="common.js"></script> -->
	<script src="background.js" type="module"></script>
</head>

<body>
</body>

</html>