<html>
<head>
<style>
div
{
width:350px;
height:100px;
border:1px solid black;
/* Internet Explorer 10 */
display:flexbox;
flex-pack:center;
flex-align:center;
/* Firefox */
display:box;
box-pack:center;
box-align:center;
/* Safari, Chrome, and Opera */
display:box;