body {
    margin: 0;
    font-family: Arial, sans-serif;
    transition: background-color 1s ease;
  }
  
  header {
    padding: 10px 20px;
    position: fixed;
    top: 20px;
    width: 100%;
    text-align: center;
    z-index: 10;
  }
  
  header nav ul {
    list-style: none;
    margin: 0;
    padding: 0;
    display: inline-flex;
  }
  
  header nav ul li {
    margin: 0 10px;
  }
  
  header nav ul li a {
    color: #000000;
    text-decoration: none;
    font-weight: bold;
  }
  
  header nav ul li a:hover {
    text-decoration: underline;
  }
  
  footer {
    text-align: center;
    padding: 10px 0;
    background-color: #333;
    color: #fff;
    position: fixed;
    width: 100%;
    bottom: 0;
    z-index: 10;
  }
  
  .gallery-container {
    overflow-y: auto;
    height: 100vh;
    margin-top: 60px;
    margin-bottom: 40px;
  }
  
  .gallery-section {
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
  }
  
  .gallery-item {
    display: flex;
    align-items: center;
    max-width: 800px;
    width: 100%;
    padding: 20px;
    box-sizing: border-box;
  }
  
  .gallery-section:nth-child(odd) .gallery-item {
    flex-direction: row;
  }
  .gallery-section:nth-child(even) .gallery-item {
    flex-direction: row-reverse;
  }
  
  .gallery-item img {
    width: 400px;
    height: auto;
    margin: 0 20px;
  }
  
  .gallery-text {
    font-size: 1.2em;
    color: #333;
  }