<!DOCTYPE html>
<html>
<head>
<style>
div {
width: 100px;
height: 100px;
background: green;
-webkit-transition: width 2s; /* For Safari 3.1 to 6.0 */
transition: width 2s;
}
div:hover {
width: 300px;
}
</style>
</head>
<body>
<h1>The transition Property</h1>
<div></div>
</body>
</html>