<!DOCTYPE html>
<html>
<head>
    <title>CSS Flexible Box Test: display proprety - flex</title>
    <link rel="author" title="haosdent" href="mailto:haosdent@gmail.com">
    <style type="text/css">
        .container {
	position: relative;
	height: 6em;
	width: 3em;
	background: red;
	margin: 1em;
	border: 1px solid black;
        }
	.success {
	background: green;
	width: 100%;
	height: 100%;
	display: block;
	}
    </style>
</head>
<body>
    <p>The test passed if you can't find red color.</p>
    <div class="container">
      <span class="success">Hello</span>
    </div>
</body>
</html>