<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style type="text/css">
div{
width:50px;
height:20px;
line-height:20px;
overflow:hidden;
border:1px solid red;
text-align:center;
}
a{
wdith:50px;
float:left;
overflow:hidden;
text-decoration:none;
}
span{
margin-top:-20px;
display:block;
}
a:hover{
padding-top:20px;
}
</style>
</head>
<body>
<div>
<a href="#">
<span> hover</span>
默认
</a>
</div>
</body>
</html>