.content{position:relative;display:block;left:0;top:0;height:300px;margin:0;padding:0}
.scroll{position:absolute;display:block;height:300px;overflow:scroll;border-right:0;left:0;top:0;width:640px;zoom:1}
.scroll_n{position:absolute;display:block;height:300px;overflow:scroll;border-right:0;left:0;top:0;width:612px;zoom:1}
.scroll_n2{position:absolute;display:block;height:300px;overflow:scroll;border-right:0;left:0;top:0;width:900px;zoom:1}
#box3{left:50px;top:350px}
#box4{left:450px;top:350px}
#changeContent{display:block;position:absolute;top:15px;left:450px;background:#999;text-decoration:none;color:#000;font-size:14px;padding:10px}
#changeContent:hover{background:#ccc}