怎样固定iframe的高度阿?
下面是我的页面,当点击两个iframe中间的按钮时,下面的iframe向上移动了,总高度发身了变化;但是我要的效果是总高度不变的情况下,下面的iframe向上移动.     
  <%@   page   contentType= "text/html;   charset=GBK "   %>  
  <html>  
  <head>  
  <title>  </title>    
  <script   type= "text/javascript "> //   Example:   obj   =   findObj( "image1 "); 
 function   findObj(theObj,   theDoc) 
 { 
       var   p,   i,   foundObj;   
       if(!theDoc)   theDoc   =   document; 
       if(   (p   =   theObj.indexOf( "? "))   >    0   &&   parent.frames.length) 
       { 
             theDoc   =   parent.frames[theObj.substring(p+1)].document; 
             theObj   =   theObj.substring(0,p); 
       } 
       if(!(foundObj   =   theDoc[theObj])   &&   theDoc.all)   foundObj   =   theDoc.all[theObj]; 
       for   (i=0;   !foundObj   &&   i    <   theDoc.forms.length;   i++) 
             foundObj   =   theDoc.forms[i][theObj]; 
       for(i=0;   !foundObj   &&   theDoc.layers   &&   i    <   theDoc.layers.length;   i++) 
             foundObj   =   findObj(theObj,theDoc.layers[i].document); 
       if(!foundObj   &&   document.getElementById)   foundObj   =   document.getElementById(theObj);   
       return   foundObj; 
 }   
  </script>  
  <style   type= "text/css ">  
  <!-- 
 .ctrlbar   { 
 	background:   #B2BFD2   url(images/bg_maincontent.gif)   left   repeat-y; 
 } 
 .explorer   { 
 	background:   #B2BFD2; 
 	border:   1px   solid   #B2BFD2; 
 } 
 .ctbutton   { 
 	font-family:   Arial,   Helvetica,   sans-serif; 
 	font-size:   8px; 
 	background-color:   #eeeeee; 
 	border-width:   1px; 
 	width:   100px; 
 	height:   10px; 
 	margin-bottom:   1px; 
 } 
 -->  
  </style>  
  </head>  
  <body>    
  <table   width= "100% "   border= "1 ">   	 
        <tr>  
              <td   width= "100% "      align= "center "   valign= "top "   class= "explorer "   id= "menubar ">  
              <iframe   name= "left "   width= "100% "   height= "100% "   scrolling= "no "   frameborder= "0 "   >  
             	       <tr>  
                                <td   width= "800 "   height= "60 ">  <img   src= "images/top.jpg "   width= "800 "   height= "60 ">  </td>  
                                <td   width= "100% "   background= "images/top_line.gif ">   </td>  
                          </tr>  
              </iframe>