table锁定列的一个方法.及琢磨思路

         div { 
            width: 600px; 
            overflow-x:scroll;  
            margin-left:5em; 
            border:1px solid red;
        }
        .headcol {
            position:absolute; 
            width:5em; 
            background-color:green;
            left:0;
            top:auto;  
        }
        .long { background:yellow; letter-spacing:1em; }

<div class='out'><div class='in'><table>
body{
    padding:20px;
}     
div.out{
    position:relative;
}
div.in { 
            width: 600px; 
            overflow-x:scroll;  
            margin-left:5em; 
            border:1px solid red;
 
        }
 
        .headcol {
            position:absolute; 
            width:5em; 
            background-color:green;
            left:0;
            top:auto;  
        }
        .long { background:yellow; letter-spacing:1em; }