<!DOCTYPE html>
<title>flexbox | flex-flow: row wrap</title>
<link rel="author" href="http://opera.com" title="Opera Software">
<style>
div {
	background: blue;
	margin: 1em 0;
	border: 1px solid black;
	width: 20em;
}
span {
	background: white;
	margin: 1em;
	width: 8em;
	display: block;
	float: left;
}
div::after {
	content: "";
	clear: both;
	display: block;
}
</style>

<div>
	<span>one</span>
	<span>two</span>
	<span>three</span>
	<span>four</span>
</div>