检测屏幕宽度，并设置为id为frame的div宽度， 根据自己网页的最大宽度来调节，小demo最大宽度为1440
<!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>
<script src="js/jquery.min.js" type="text/javascript"></script>
<script>
function onWidthChange(){
var w=$(window).width();
x=(w-1440)/2;
$("#frame").css("width",w);
if(w<1024){
$("#frame").css("overflow","visible");
$("#webContent").css("margin-left",x);
}else if(1024<w<1440){
$("#frame").css("overflow","hidden");
$("#webContent").css("margin-left",x);
}
setTimeout(onWidthChange,0);
};
</script>
</head>
<body>
<div id="frame" style="overflow:hidden;">
<div id="webContent">
//内容
</div>
</div>
</body>
</html>