<!DOCTYPE html>
<meta charset="utf-8">
<title>White square reference</title>
<style>
    body { background-color: grey; }
    .test { background-color: #FFFFFF; width: 12em; height: 12em; }
</style>
<body>
    <p>Test passes if you see a white square, and no red.</p>
    <div class="test"></div>
</body>