console 命令行工具 X clear
console
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .header,
        .footer {
             height: 100px;
             background-color: gray;
        }

        .left{
            height: 500px;
            width: 50%;
            float: left;
            background-color: red;
        }

         .right1,
         .right2{
            height: 250px;
            width: 50%;
            float: left;
         }

         .right1 {
            background-color:yellow;
         }

         .right2 {
            background-color:blue;
         }

         .clearfix::after{
             content:"";
             display: table;
             clear: both;
         }

         h1{
             margin: auto auto;
             width: 300px;
             line-height: 100px;
         }
    </style>
</head>

<body>
    
    <div class="header">
        <h1>header</h1>
    </div>
    
    <div class="content clearfix">
        <div class="left">
            <h1>left</h1>
    </div>
    <div class="right1">
        <h1>top-right</h1>
    </div>
    <div class="right2">
        <h1>bottom-right</h1>
    </div>
    </div>
    <div class="footer">
        <h1>footer</h1>
    </div>
    
</body>
</html>