flex实现圣杯布局，再也不用定位了！效果图代码思考如何让mid块优先加载？？？

效果图

面试官说请实现一个两边等宽中级自适应的布局

代码

通过给子元素设置flex-grow属性，可以按比例分配父元素宽度

<!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>
    html,
    body {
      height: 100%;
      margin: 0;
      padding: 0;
    }

    .header,
    .footer {
      height: 50px;
      background: green;
    }

    .main {
      display: flex;
      flex-direction: row;
      justify-content: space-between;
      height: calc(100% - 100px);
    }

    .left {
      /* flex-grow: 1; */
      width: 100px;
      background-color: red;
    }

    .mid {
      flex-grow: 1;
      background-color: chartreuse;
    }

    .right {
      /* flex-grow: 1; */
      width: 100px;
      background-color: blueviolet;
    }
  </style>
</head>

<body>
  <div class="header">header</div>
  <div class="main">
    <div class="left">left</div>
    <div class="mid">mid</div>
    <div class="right">right</div>
  </div>
  <div class="footer">footer</div>
</body>

</html>

思考

如何让mid块优先加载？？？