console 命令行工具 X clear
console
<html>

<head>
  <meta charset="UTF-8">
  <title>Document</title>
  <style>
  * {
    padding: 0;
    margin: 0;
    border: none;
  }
    
  body {
    display: flex;
  }

  .arrow-code-box {
    width: 100px;
    height: 100px;
    margin: auto;
    overflow: hidden;
    background: #fcfcfc;
  }
  
  .arrow-code {
    width: 100px;
    height: 100px;
    position: relative;
    background: transparent;
  }
  
  .arrow-code:before,
  .arrow-code:after {
    content: " ";
    display: block;
    position: absolute;
    
  }
  
  .arrow-code:after {
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    /*background: #ffffff;*/
    background: transparent;
    width: 150px;
    height: 150px;
    top: -82px;
    left: -75px;
    box-shadow: 0 0 10px 10px rgba(0, 0, 0, .2);
    transform: rotate(45deg);
  }

  .arrow-code:before {
    height: 5px;
    width: 5px;
    right: 0;
    bottom: 0;
    background: #2d2d2d;
    box-shadow: 0 -7px 0 #2d2d2d,
      0 -14px 0 #2d2d2d,
      0 -21px 0 #2d2d2d,
      0 -28px 0 #2d2d2d,
      0 -35px 0 #2d2d2d,
      0 -42px 0 #2d2d2d,
      0 -49px 0 #2d2d2d,
      0 -56px 0 #2d2d2d,
      -7px 0 0 #2d2d2d,
      -14px 0 0 #2d2d2d,
      -21px 0 0 #2d2d2d,
      -28px 0 0 #2d2d2d,
      -35px 0 0 #2d2d2d,
      -56px 0 0 #2d2d2d,
      -62px 0 0 #2d2d2d,
      -7px -7px 0 #2d2d2d,
      -14px -7px 0 #2d2d2d,
      -21px -7px 0 #2d2d2d,
      -28px -7px 0 #2d2d2d,
      -35px -7px 0 #2d2d2d,
      -42px -7px 0 #2d2d2d,
      -49px -7px 0 #2d2d2d,
      -56px -7px 0 #2d2d2d,
      -63px -7px 0 #2d2d2d,
      -63px -7px 0 #2d2d2d,
      -63px -7px 0 #2d2d2d,
      -63px -7px 0 #2d2d2d,
      -63px -7px 0 #2d2d2d,
      -63px -7px 0 #2d2d2d,
      -63px -7px 0 #2d2d2d,
      -63px -7px 0 #2d2d2d,
      -63px -7px 0 #2d2d2d,
      -63px -7px 0 #2d2d2d;
  }
  </style>
</head>

<body>
  <div class="arrow-code-box">
    <div class="arrow-code"></div>
  </div>
</body>

</html>