<!DOCTYPE html>
<html>
<head>
    <title>CSS Flexible Box Test: align-content property - center</title>
    <link rel="author" title="haosdent" href="mailto:haosdent@gmail.com">
    <style type="text/css">
        .container {
	position: relative;
	height: 6em;
	width: 20em;
	background: red;
	margin: 1em;
	border: 1px solid black;
        }
	span:nth-child(3), span:nth-child(4) {
	margin: 2em 1em;
	}
	span {
	height: 2em;
	display: inline-block;
	background: green;
	color: white;
	margin: 0 1em;
	width: 8em;
	float: left;
	}
    </style>
</head>
<body>
    <p>The test passed if you see a centered 2*2 table.</p>
    <div class="container">
      <span>first</span>
      <span>second</span>
      <span>third</span>
      <span>forth</span>
    </div>
</body>
</html>