双飞翼布局

<style>
        *{
            margin:0;padding:0;
            /* color:#fff; */
        }
        .header{
            background: orange;
            height:150px;
        }
        
        .footer{
            background: pink;
            height:100px;
        }
        .middle{
            background: green;
            height:300px;
            overflow: hidden;
        }
        .left{
            float:left;
            background: blue;
            color:#fff;
            width:150px;
            height:16px;
            margin-left:-100%;
            margin-bottom:-9999px;
            padding-bottom: 9999px;
        }
        .mid{
            background: red;
            float:left;
            width:100%;
            
        }
        .inner{
            margin-left:150px;
            margin-right:100px;
            background: yellow;
            /* margin-bottom:-9999px;
            padding-bottom: 9999px; */
            }
        .right{
            float:right;
            background: aquamarine;
            width:100px;
            height:16px;
            margin-left:-100%;
            /* margin-bottom:-9999px;     设置3个等高：先用padding撑开，为不影响下面元素，再用margin：-9999px收回
            padding-bottom: 9999px; */    
        }
    </style>

<div class="header">我是头</div>
    <div class="middle">
        <div class="mid"><div class="inner">我是中间 ，是重要部分</div></div>     

        <div class="left">我是左</div>
        
        <div class="right">我是右</div>
        
    </div>
    <div class="footer">我是尾</div>