覆盖整个browser的半透明div弹出div

/************ajaxpost.js*************************


$(document).ready(function(){
    hideAll();
});
function hideAll(){
    $("#divShow").hide();
    $("#divDlg").hide();
}
    function showDiv(){
        $("#divShow").show();
        $("#divDlg").show();    }
    var pid=-1;
    function doModify(tid){
        showDiv();    
        $("#theName").html(tid);
        pid=tid;
    }    
    function updateModify(){
        var pwd1=$("#pwd1").val();
        var pwd2=$("#pwd2").val();
        if(pwd1==0 || pwd2==0 ){
            alert("密码不能为空，请重新输入！");
            return false;
        }
        
        if(pwd1!=pwd2){
            alert("两次输入的密码不一致，请重新输入！");
            return false;
        }
        
        $.post("zModifyPwd.asp",{id:pid,pwd:pwd1,verycode:"1w2c3g4s5u6p7e8r"},function(data){
            if(data==1){
                alert("密码修改成功！\n请妥善保管好您的密码.");
                hideAll();
                $("#pwd1").val("");
                $("#pwd2").val("");
            }
            else{
                alert("密码提交时发生异常!保存失败.");
            }
        });    
    }

/****************************************/



<script type="text/javascript" src="../js_me/jquery-1.2.5.pack.js"></script>
<script type="text/javascript" src="../js_me/ajaxpost.js"></script>    
    <style type="text/css">
    #divShow{
    position:absolute;
    z-index:999;    
    width:100%;
    height:100%;
    filter:alpha(opacity=70);
     -moz-opacity:0.70;
     opacity:0.70;
    background-color:#000;
    left:0;
    top:0;
    text-align:center;
    vertical-align:middle;
    }
#divDlg {
    position:absolute;    
    height:100%;
    width:100%;
    text-align:center;
    vertical-align:middle;    
    z-index:1000;    
    color:#000; 
    font-size:13px;
    left:0;
    top:0;    
}
</style>





<div id="divShow"></div>
<div id="divDlg">
<form id="frmAjax" name="form1" method="post" action="">
<table bgcolor="#CCCCCC" width="375" height="122" border="1" cellpadding="0" cellspacing="0" bordercolor="#aaa" 
style=" border-collapse:collapse; margin:150 auto;">
  <tr>
    <td colspan="2" align="center">&nbsp;你要修改的用户ID为：
    <span id="theName" style=" font-size:14px; color:red; font-weight:bold;" >&nbsp;</span></td>
  </tr>
  <tr>
    <td colspan="2" align="center">
    较安全的密码应包含字母数字特殊符号，如<span style=" font-size:14px; color:red; font-weight:bold;">xyz123&(*hello<span>
    </td>
  </tr>
  
  <tr>
    <td width="138" align="right">您的新密码：</td>
    <td width="231"> 
      <input type="password" onMouseOver="javascript:this.select();" name="pwd1" id="pwd1" />
   
    </td>
  </tr>
  <tr>
    <td align="right">请再次输入：</td>
    <td><input type="password" onMouseOver="javascript:this.select();" name="pwd2" id="pwd2" /></td>
  </tr>
  <tr>
    <td colspan="2" align="center">
    <input name="btnSubmit" type="button" id="btnSubmit" value="按钮" onClick="javascript:updateModify();" />
    &nbsp;&nbsp;
      <input type="button" name="Submit2" value="关闭" onClick="javascript:hideAll();" /></td>
  </tr>
</table>
</form>
</div>