<style type="text/css">  
    #login  
    {  
        display: none;  
        border:10px solid #ddd;  
        position: fixed;
		top: 20%;
        height:60%;  
        width:60%;  
        background: white;  
        margin: -100px 0px 0px -150px;
    }  
    #over  
    {  
        width: 100%;  
        opacity:0.8;/*設定背景色透明度,1為完全不透明,IE需要使用filter:alpha(opacity=80);*/  
        filter:alpha(opacity=80);  
        display: none;  
        position:absolute;  
        top:0;  
        left:0;  
        z-index:2;  
        background: silver;  
    }  
    </style> 
 

<script type="text/javascript">

		function show()  
	    {  
	    	document.getElementById("login").style.display = "block";  
	        document.getElementById("over").style.display = "block";  
			document.getElementById("over").style.height=document.body.scrollHeight;
			document.getElementById("login").style.left=(document.body.scrollWidth-document.getElementById("login").scrollWidth)/2+"px";
	    }  
	    function hide()  
	    {  
	    	document.getElementById("login").style.display = "none";  
	    	document.getElementById("over").style.display = "none";  
	    }

	</script>
 

<div id="login">
		<iframe id="form1" src=""
	 name="activiProcess" frameborder="0" marginheight="0" marginwidth="0"
	  height="100%" width="100%"></iframe>
		
  </div>
  <div id="over" onclick="hide()"></div>