该写法源自：http://sg.8864.com/
<!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 content="text/html; charset=utf-8" http-equiv="Content-Type">
<style type="text/css">
*{ margin:0px; padding:0px; border:0 none; }
.menu{504px;height:90px;background:url(./bj_2.jpg) no-repeat -200px 0;float:right;}
.menu a{display:block;126px;height:90px;float:left;background:url(./bj_2.jpg) no-repeat;}
.menu a.a_1{background-position:-200px 0;}
.menu a.a_1:hover{background-position:-704px 0;}
.menu a.a_2{background-position:-326px 0;}
.menu a.a_2:hover{background-position:-830px 0;}
.menu a.a_3{background-position:-452px 0;}
.menu a.a_3:hover{background-position:-956px 0;}
.menu a.a_4{background-position:-578px 0;}
.menu a.a_4:hover{background-position:-1082px 0;}
</style>
</head>
<body>
<div class="menu">
<a class="a_1" ></a>
<a class="a_2" ></a>
<a class="a_3" ></a>
<a class="a_4" ></a>
</div>
</body>
</html>