<!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>