<!DOCTYPE html>
<html>
<head>
    <title>Reference File</title>
    <link rel="author" title="Zhang Xiaochong" href="mailto:joy.xczhang@gmail.com">
    <style type="text/css">
        .container {
            position: relative;
        }
        .ref {
            background-color: green;
            height: 160px;
            left: 5px;
            position: absolute;
            top: 5px;
            width: 160px;
        }
    </style>
</head>
<body>
    <p>The test passes if there is a filled green square and no red.</p>
    <div class="container">
        <div class="ref"></div>
    </div>
</body>
</html>