<!DOCTYPE html>
<title>flexbox | vertical-align</title>
<link rel="author" href="http://opera.com" title="Opera Software">
<style>
div {
	background: yellow;
	border: 1px solid black;
	width: 600px;
}
p {
	background: #3366cc;
	margin: 2em;
	width: 2em;
	height: 2em;
	float: left;
}
div::after {
	content: "";
	clear: both;
	display: block;
}
</style>

<div>
	<p></p>
	<p></p>
	<p></p>
	<p></p>
	<p></p>
</div>