为什么不能居中呢？
<!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>FOR U 10000</title>
<style type="text/css">
body{margin:0;padding: 0;font-family: "miscrosoft yahei,sans-serif";text-align:center;}
#warp{width:800px;maigin:0px auto;border:1px solid #66ccff;}
#head{}
#main{}
.h1{}
.p1{}
.p2{}
#foooter{}
</style>
</head>
<body>
<div id=warp>
<div id="head"></div>
<div id="main">
<div class="h1">
<h1>grace</h1>
</div>
<div class="p1">
<h2>beagticfor name</h2>
<p>sffef sdefa efadf efafd</p>
</div>
<div class="p2"></div>
<h2>beagticfor name</h2>
<p>sffef sdefa efadf efafd</p>
</div>
<div id="foooter"></div>
</div>
</body>
</html>为什么不能居中？
