CSS3【display: flex；】自适应布局案例

<!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>
    * {
      margin: 0;
      padding: 0;
      list-style: none;
    }
    h3 {
      margin: 20px 0 10px 100px;
      font-weight: normal;
    }
    /* 导航栏自适应布局 */
    ul {
      width: 600px;
      margin-left: 100px;
      display: flex;
      border: 1px solid #000;
    }
    ul li {
      flex: 1;
      text-align: center;
      line-height: 60px;
      background-color: pink;
      margin: 0 5px;
    }
    /* 网页自适应布局 */
    .layout {
      width: 600px;
      height: 400px;
      border: 1px solid #000;
      margin-left: 100px;
      /* 伸缩布局 */
      display: flex;
      /* 主轴方向 */
      flex-direction: column;
    }
    .header {
      background-color: pink;
      flex: 1;
    }
    .section {
      background-color: red;
      flex: 5;
      display: flex;
    }
    .left {
      flex: 1;
      background-color: orange;
    }
    .right {
      flex: 3;
      background-color: #f40;
    }
    .footer {
      background-color: #222;
      flex: 1;
    }
  </style>
</head>
<body>
  <h3>导航栏自适应布局</h3>
  <ul>
    <li>消息</li>
    <li>消息</li>
    <li>消息</li>
    <li>消息</li>
    <li>消息</li>
  </ul>
  <h3>网页自适应布局</h3>
  <div class="layout">
    <div class="header"></div>
    <div class="section">
      <div class="left"></div>
      <div class="right"></div>
    </div>
    <div class="footer"></div>
  </div>
</body>
</html>