<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style type="text/css">
#a
{
top:200px;
left:350px;
50px;
height:50px;
-moz-border-radius:15px;
-webkit-border-radius:15px;
border-radius:25px;/*倒角半径*/
/*阴影*/box-shadow: 5px/*左右偏移，负值左，正值右*/ 3px/*上下偏移，负值上，正值下*/ 25px/*虚化度，值越大越虚*/ red;
background-color:#0F0;
position:absolute;}
</style>
</head>
<body>
<div id="a"></div>
</body>