<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style type="text/css">
*{margin: 0; padding: 0;}
ul{
1080px;
height:632px;
overflow: hidden;
}
ul li{
70px;
height: 632px;
float: left;
list-style: none;
transition:width 0.5s;
}
.on{
800px;
}
</style>
<script type="text/javascript" src="js/jquery-1.7.2.min.js"></script>
<script>
$(function(){
$('ul li').mouseover(
function() {
$(this).addClass('on').siblings().removeClass('on');
})
})
</script>
</head>
<body>
<ul>
<li>
<a href="javascript:;">
<img src="images/num-01.jpg">
</a>
</li>
<li >
<a href="javascript:;">
<img src="images/num-02.jpg">
</a>
</li>
<li>
<a href="javascript:;">
<img src="images/num-03.jpg">
</a>
</li>
<li >
<a href="javascript:;">
<img src="images/num-04.jpg">
</a>
</li>
<li class="on">
<a href="javascript:;">
<img src="images/num-05.jpg">
</a>
</li>
</ul>
</body>
</html>