test/site/four.html

<!DOCTYPE html>
<html>
<head>
    <title>four</title>
</head>
<body>
    <div id="container" style="width: 200px; height: 10px; background: white">
        <div id="difference" style="width: 1px; height: 1px; background: red"></div>
    </div>
</body>
</html>