それを自分で試してみてください - JavaScript Reference style

<!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: 1;}
#main div:nth-of-type(3) {-webkit-flex-grow: 1;}

/* Standard syntax */
#main div:nth-of-type(1) {flex-grow: 1;}
#main div:nth-of-type(2) {flex-grow: 1;}
#main div:nth-of-type(3) {flex-grow: 1;}
</style>
</head>
<body>

<p>Click the "Try it" button to set the value of the flexGrow property to "5" for the blue div element</p>

<p><b>Note:</b> Internet Explorer 10 and earlier versions earlier versions do not support the flexGrow property.</p>

<p><b>Note:</b> Safari 6.1 (and newer) supports an alternative, the WebkitFlexGrow property.</p>

</body>
</html>