fieldset{padding:0 15px 10px 15px;}
<h3>?????</h3>
<div id="header"><h1></h1></div>
<body>
h1{font-size:2.4em;margin:0;color:#FFF;}
<html xmlns="3./1999/xhtml">
<div class="tent-tainer"><fieldset>
background-color:#555555;}
</div>
<meta http-equiv="tent-Type" tent="text/html; charset=gb2312"/>
.tent-tainer{background:#FFF;width:96%;margin-top:8px;padding:10px;positioive;}
</fieldset></div>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "3./TR/xhtml1/DTD/xhtml1-strict.dtd">
<title>500 - ?</title>
-->
#header{width:96%;margin:0 0 0 0;padding:6px 2% 6px 2%;font-family:"trebuchet MS", Verdana, sans-serif;color:#FFF;
h3{font-size:1.2em;margin:10px 0 0 0;color:#000000;}
<style type="text/css">
</body>
</style>
<!--
<h2>500 - ?</h2>
body{margin:0;font-size:.7em;font-family:Verdana, Arial, Helvetica, sans-serif;background:#EEEEEE;}
h2{font-size:1.7em;margin:0;color:#CC0000;}
</html>
<head>
<div id="tent">
#tent{margin:0 0 0 2%;positioive;}
</head>