<!DOCTYPE html>
<meta charset="utf-8">
<title>Reference for negative margins</title>
<link rel="author" title="Google Inc." href="https://www.google.com/">
<style>
    .container {
        width: 40px;
        height: 10px;
        background-color: green;
        border: 3px black solid;
    }
</style>
<body>
    <p>You should see a green rectangle with a black border, 40px wide. You should see no red.</p>

    <div class="container">
    </div>
</body>
