<!DOCTYPE html>
<html>
<head>
<style>
#main {
width: 70px;
height: 300px;
border: 1px solid #c3c3c3;
display: -webkit-flex;
display: flex;
-webkit-flex-wrap: wrap;
flex-wrap: wrap;
-webkit-align-content: center;
align-content: center;
}
#main div {
width: 70px;
height: 70px;
}
</style>
</head>
<body>
<div id="main">
<div style="background-color:coral;"></div>
<div style="background-color:lightblue;"></div>
<div style="background-color:pink;"></div>
</div>
<p><b>Note:</b> Internet Explorer 10 and earlier versions do not support the align-content property.</p>
<p><b>Note:</b> Safari 7.0 (and newer) supports an alternative, the -webkit-align-content property.</p>
</body>
</html>