<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Security-Policy" content="upgrade-insecure-requests">
<link rel="stylesheet" href="http://127.0.0.1:8443/security/mixedContent/resources/style.css">
</head>
<body>
This background color should be blue.
<script>
if (window.opener)
    window.opener.postMessage('done', '*');
</script>
</body>
</html>