lab/exercise-css/lowyingxi/cssfile/style-adaptive.css
body {
    margin: 0;
    padding: 0;
    font-family: Arial, sans-serif;
  }
  
  header {
    background-color: #0072c6;
    color: #fff;
    padding: 20px;
  }
  
  nav {
    background-color: #eee;
    padding: 10px;
  }
  
  nav ul {
    margin: 0;
    padding: 0;
    list-style: none;
  }
  
  nav li {
    display: inline-block;
    margin-right: 10px;
  }
  
  nav a {
    color: #000;
    text-decoration: none;
    padding: 5px;
  }
  
  nav a:hover {
    background-color: #0072c6;
    color: #fff;
  }
  
  main {
    padding: 20px;
  }
  
  section {
    margin-bottom: 20px;
  }
  
  section h2 {
    font-size: 24px;
    margin-bottom: 10px;
  }
  
  section ul {
    margin: 0;
    padding: 0;
    list-style: none;
  }
  
  footer {
    background-color: #ccc;
    padding: 10px;
    text-align: center;
  }
  
  @media only screen and (min-width: 768px) {
    header {
      display: flex;
      flex-wrap: wrap;
    }
  
    nav {
      flex: 1;
      margin-left: 20px;
    }
  
    main {
      margin-left: 20px;
    }
  }
  
  @media only screen and (min-width: 1024px) {
    header {
      display: flex;
    }
  
    nav {
      order: 2;
    }
  
    main {
      order: 1;
      flex: 3;
    }
  
    section {
      flex: 1;
      margin-left: 20px;
    }
  }
  