<title>无标题文档</title>
<style type="text/css">
.a
{
height:40px;
80px;
position:absolute;
}
#a
{
background-color:#00C;
top:200px;
left:300px;
overflow:hidden;
}
#b
{
background-color:#C00;
height:120px;
80px;
top:40px;
left:0px;
position:absolute;
}
#b1
{
background-color:#FF0;
top:0px;
0px;
position:absolute;
}
#b2
{
background-color:#0FF;
top:40px;
left:0px;
position:absolute;
}
#b3
{
background-color:#000;
top:80px;
0px;
position:absolute;
}
</style>
</head>
<body>
<divclass="a" id="a" onmouseover="over1()" onmouseout="out1()" >
<div id="b">
<div class="a" id="b1"></div>
<div class="a" id="b2"></div>
<div class="a" id="b3"></div>
</div>
</div>
</body>
</html>