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console 命令行工具 X clear

                    
>
console
<div class="container"> 
  <div class="main">main</div>
  <div class="left">left</div>
  <div class="right">right</div>
</div>
   *{margin:0;padding:0;}
    .container {
        padding: 0 300px 0 200px;
        min-width:200px;

    }
    .left, .main, .right {
        position: relative;
        min-height: 130px;
        float: left;
    }
    .left {
        left: -200px;
        margin-left: -100%;
        background: green;
        width: 200px;
    }
    .right {
        right: -300px;
        margin-left: -300px;
        background-color: red;
        width: 300px;
    }
    .main {
        background-color: blue;
        width: 100%;
    }