我的答案对不对,任务3错哪里了
*{margin:0; padding:0;}
#wrap{width:970px; margin:0 auto;}
#mainbody{ margin-top:15px; position:relative;}
#left{ width:110px; float: left; }
#mid{width:650px;border:1px solid #999; float: left; margin-left:13px;}
#right{border:1px solid #999; position:absolute; margin-left:776px;}