<!DOCTYPE html>
<html>
<head>
<style>
#main {
width: 350px;
height: 100px;
border: 1px solid #c3c3c3;
display: -webkit-flex; /* Safari */
display: flex;
}
/* Safari 6.1+ */
#main div:nth-of-type(1) {-webkit-flex-grow: 1;}
#main div:nth-of-type(2) {-webkit-flex-grow: 3;}
#main div:nth-of-type(3) {-webkit-flex-grow: 1;}
#main div:nth-of-type(4) {-webkit-flex-grow: 1;}
#main div:nth-of-type(5) {-webkit-flex-grow: 1;}
/* Standard syntax */
#main div:nth-of-type(1) {flex-grow: 1;}
#main div:nth-of-type(2) {flex-grow: 3;}
#main div:nth-of-type(3) {flex-grow: 1;}
#main div:nth-of-type(4) {flex-grow: 1;}
#main div:nth-of-type(5) {flex-grow: 1;}
</style>
</head>
<body>
<div id="main">
<div style="background-color:coral;"></div>
<div style="background-color:lightblue;"></div>
<div style="background-color:khaki;"></div>
<div style="background-color:pink;"></div>
<div style="background-color:lightgrey;"></div>
</div>
<p><b>Note:</b> Internet Explorer 10 and earlier versions do not support the flex-grow property.</p>
<p><b>Note:</b> Safari 6.1 (and newer) supports an alternative, the -webkit-flex-grow property.</p>
</body>
</html>