做了个弹窗放百度地图 为什么百度地图的中心点在左上角

不要一開始就加載地圖<!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>窗口</title>
<style type="text/css">
*{margin:0;padding:0;}
.theme-buy{margin-top:7%;text-align:center;}
.theme-signin{font-size:15px;}
.theme-popover-mask{z-index:1;position:absolute;left:0;top:0;width:100%;height:100%;background:#000;opacity:0.5;filter:alpha(opacity=50);-moz-opacity:0.5;display:none;}
.theme-popover{z-index:9;position:absolute;top:50%;left:50%;width:660px;height:360px;margin:-180px 0 0 -330px;border-radius:5px;border:solid 2px #e4e4e4;background-color:#fff;display:none;box-shadow:0 0 10px #666;background:#fff;}
.theme-poptit{border-bottom:1px solid #ddd;padding:12px;position:relative;height:24px;}
.theme-poptit .close{float:right;color:#999;padding:5px;margin:-2px -5px -5px;font:bold 14px/14px simsun;text-shadow:0 1px 0 #ddd}
.theme-poptit .close:hover{color:#444;}
.theme-popbod{width:600px;height:300px;}
#allmap{width:660px;height:300px;}
</style>
<script type="text/javascript" src="http://api.map.baidu.com/api?v=2.0&ak=6066cf2819dbd803b5a1799007d7e3e0"></script>
<script type="text/javascript" src="http://code.jquery.com/jquery-1.10.2.min.js"></script>
<script type="text/javascript">
$(document).ready(function($){
  var map, er1, infoWindow1;
 
    $('.theme-login').click(function(){
        $('.theme-popover-mask').show();
        $('.theme-popover-mask').height($(document).height());
        $('.theme-popover').show();
if(!map) {
// 百度地图API功能
map = new BMap.Map("allmap");
map.centerAndZoom(new BMap.Point(116.404, 39.915), 14);
er1 = new BMap.Marker(new BMap.Point(116.384, 39.925));  // 创建标注
map.addOverlay(er1);              // 将标注添加到地图中
 
//创建信息窗口
infoWindow1 = new BMap.InfoWindow("普通标注");
er1.addEventListener("click", function(){this.openInfoWindow(infoWindow1);});
}
    })
    $('.theme-poptit .close').click(function(){
        $('.theme-popover-mask').hide();
        $('.theme-popover').hide();
    })
    $('.theme-popover-mask').click(function(){
    $('.theme-poptit .close').click()
});
});
</script>
     
</head>
 
<body>
<div class="theme-buy">
    <a class="theme-login" href="javascript:;">点击查看效果</a>
</div>
 
<div class="theme-popover-mask"></div>
 
<div class="theme-popover">
    <div class="theme-poptit">
        <a href="javascript:;" title="关闭" class="close">×</a>
        <h3>弹窗</h3>
    </div>
    <div class="theme-popbod">
        <div id="allmap"></div>
    </div>
</div>
</body>
</html>