FF不支持position:relative吗?
看下面的代码,改变style.posTop,posLeft属性,可以以p元素上下移动,在IE和opera里面都工作正常,可是在FF里面一定反应都没有, 
 什么原因,   
 代码如下:   
  <!DOCTYPE   html   PUBLIC    "-//W3C//DTD   HTML   4.01   Transitional//EN "    "http://www.w3.org/TR/html4/loose.dtd ">  
  <html>  
  <head>  
  <meta   http-equiv= "Content-Type "   content= "text/html;   charset=GB18030 ">  
  <title> Insert   title   here </title>  
  <style   type= "text/css ">  
 #a{background-color:red;border:1px   solid   black;position:relative;} 
 #b{background-color:blue;border:1px   solid   black;}   
  </style>  
  </head>  
  <body>  
  <p   id= "a "> aaaaaaaaaaaaaaaaa </p> cccc 
  <p   id= "b "> bbbbbbbbbbbbbbbb </p>  
  <button   onclick= "down() "> 下移 </button>  
  </body>  
  <script   type= "text/javascript ">  
 function   down(){ 
    p   =   document.getElementById( "a "); 
       //alert(p.style.position); 
    //alert(p.style.posTop); 
    //alert(p.style.posLeft); 
    p.style.posTop   =p.style.posTop   +   10; 
       p.style.posLeft   =p.style.posLeft   +   20;   
 } 
  </script>  
  </html>
------解决方案--------------------请使用 
 document.getElementByID( "id ").style.left =  "123px ";  
 document.getElementByID( "id ").style.top =  "123px ";    
 另外,一定要加单位 "122px "
------解决方案--------------------var temp = parseInt(p.style.posTop)+20; 
 p.style.posTop = temp +  "px "; 
------解决方案--------------------var temp = parseInt(p.style.top)+20; 
 p.style.top = temp +  "px "; 
 temp = parseInt(p.style.left)+20; 
 p.style.left = temp +  "px ";