body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
  }
  
  header {
    background-color: #333;
    color: #fff;
    padding: 10px 0;
  }
  
  nav ul {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    flex-wrap: nowrap;
  }
  
  nav ul li {
    display: inline-block;
    margin-right: 20px;
  }
  
  nav ul li a {
    color: #fff;
    text-decoration: none;
  }
  
  main {
    padding: 20px;
  }
  
  .banner {
    text-align: center;
    background-image: url('lien_vers_image_banner.jpg');
    background-size: cover;
    color: #fff;
    padding: 100px 0;
  }
  
  .banner h1 {
    font-size: 3em;
  }
  
  .banner p {
    font-size: 1.5em;
  }
  
  .btn {
    display: inline-block;
    padding: 10px 20px;
    background-color: #FF0000;
    color: #fff;
    text-decoration: none;
    border-radius: 5px;
    margin-top: 20px;
  }
  
  .btn:hover {
    background-color: #990000;
  }
  
  footer {
    background-color: #333;
    color: #fff;
    text-align: center;
    padding: 10px 0;
    position: absolute;
    bottom: 0;
    width: 100%;
  }

  .burger {
    display: none;
    cursor: pointer;
  }
  
  .line1, .line2, .line3 {
    width: 25px;
    height: 3px;
    background-color: #333;
    margin: 5px;
    transition: all 0.3s ease;
  }
  
  @media screen and (max-width: 768px) {
    .nav-links {
      display: none;
      width: 100%;
      text-align: center;
      position: absolute;
      background-color: #f9f9f9;
      top: 80px;
      left: 0;
    }
  
    .nav-links li {
      display: block;
      margin-top: 10px;
    }
  
    .burger {
      display: block;
    }
  }