haojie.shi
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AHRD_XF_SYSTEM


			
				
					
						
						
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							<!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>
      .box {
        width: 100px;
        height: 400px;
        background: black;
      }
      .parent {
        width: auto;
        height: auto;
        background: red;
      }
      .child {
        width: 400px;
        height: 200px;
      }
    </style>
  </head>
  <body>
    <div class="box">
      <div class="parent">
        <div class="child"></div>
      </div>
    </div>
  </body>
</html>