:root {
    --primary: #8B4513;
    --secondary: #FFFDD0;
    --accent: #00BFFF;
    --highlight: #FF69B4;
    --text: #333;
    --light: #F5F5DC;
    --dark: #1A1A1A;
  }

  @font-face {
    font-family: 'Retro';
    src: local('Times New Roman'), local('Georgia');
  }

  @font-face {
    font-family: 'Modern';
    src: local('Arial'), local('Helvetica');
  }

  * {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }

  body {
    background: radial-gradient(circle at 20% 30%, var(--secondary), var(--light));
    color: var(--text);
    font-family: 'Modern', sans-serif;
    line-height: 1.6;
    min-height: 100%;
    overflow-x: hidden;
  }

  .header {
    position: relative;
    height: 80vh;
    max-height: 800px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 2rem;
    background: linear-gradient(135deg, rgba(139,69,19,0.8), rgba(255,255,255,0.2));
    clip-path: polygon(0 0, 100% 0, 100% 85%, 0 100%);
    margin-bottom: 5rem;
  }

  .header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('https://images.gptkong.com/demo/sample3.png') center/cover no-repeat;
    opacity: 0.2;
    z-index: -1;
  }

  .header h1 {
    font-family: 'Retro', serif;
    font-size: 4rem;
    color: var(--primary);
    text-shadow: 3px 3px 0 rgba(0,0,0,0.1);
    margin-bottom: 2rem;
    animation: fadeIn 1.5s ease;
  }

  .header p {
    font-size: 1.5rem;
    max-width: 800px;
    margin: 0 auto 3rem;
    color: var(--dark);
  }

  .reference {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background: rgba(255,255,255,0.9);
    padding: 10px 15px;
    border-radius: 30px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    font-size: 0.9rem;
    z-index: 100;
  }

  .container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
  }

  article {
    background: white;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    padding: 3rem;
    margin-bottom: 5rem;
    position: relative;
    overflow: hidden;
  }

  article::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 5px;
    height: 100%;
    background: linear-gradient(to bottom, var(--primary), var(--highlight));
  }

  h2, h3 {
    font-family: 'Retro', serif;
    color: var(--primary);
    margin: 2rem 0 1.5rem;
    position: relative;
    padding-left: 1.5rem;
  }

  h2 {
    font-size: 2.2rem;
    border-bottom: 2px dashed var(--primary);
    padding-bottom: 0.5rem;
  }

  h3 {
    font-size: 1.8rem;
  }

  h2::before, h3::before {
    content: '';
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 10px;
    height: 10px;
    background: var(--highlight);
    border-radius: 50%;
  }

  p {
    margin-bottom: 1.5rem;
    font-size: 1.1rem;
  }

  pre {
    background: #f8f8f8;
    border-left: 4px solid var(--accent);
    border-radius: 0 5px 5px 0;
    padding: 1.5rem;
    margin: 2rem 0;
    overflow: auto;
    font-family: monospace;
    font-size: 0.95rem;
    line-height: 1.5;
    position: relative;
  }

  pre::before {
    content: 'CSS';
    position: absolute;
    top: 0;
    right: 0;
    background: var(--accent);
    color: white;
    padding: 0.2rem 0.8rem;
    font-size: 0.8rem;
    border-radius: 0 0 0 5px;
  }

  code {
    font-family: monospace;
    background: rgba(0,191,255,0.1);
    padding: 0.2rem 0.4rem;
    border-radius: 3px;
    color: #0066cc;
  }

  .image-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
    margin: 3rem 0;
  }

  .image-card {
    background: white;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
  }

  .image-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 30px rgba(0,0,0,0.2);
  }

  .image-card img {
    width: 100%;
    height: 300px;
    object-fit: cover;
    display: block;
  }

  .image-caption {
    padding: 1.5rem;
    background: linear-gradient(to right, var(--secondary), white);
  }

  ol, ul {
    margin-left: 2rem;
    margin-bottom: 2rem;
  }

  li {
    margin-bottom: 0.8rem;
    position: relative;
  }

  li::before {
    content: '';
    position: absolute;
    left: -1.5rem;
    top: 0.7rem;
    width: 8px;
    height: 8px;
    background: var(--highlight);
    border-radius: 50%;
  }

  .nav-links {
    position: sticky;
    top: 2rem;
    align-self: start;
    background: white;
    padding: 1.5rem;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
  }

  .nav-links h4 {
    font-family: 'Retro', serif;
    color: var(--primary);
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px dashed var(--primary);
  }

  .nav-links ul {
    list-style: none;
    margin: 0;
  }

  .nav-links li {
    margin-bottom: 0.5rem;
  }

  .nav-links a {
    color: var(--text);
    text-decoration: none;
    display: block;
    padding: 0.5rem 0;
    transition: color 0.3s ease;
    position: relative;
  }

  .nav-links a:hover {
    color: var(--highlight);
  }

  .nav-links a::before {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--highlight);
    transition: width 0.3s ease;
  }

  .nav-links a:hover::before {
    width: 100%;
  }

  @keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
  }

  @keyframes pulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.05); }
    100% { transform: scale(1); }
  }

  @media (max-width: 768px) {
    .header h1 {
      font-size: 2.5rem;
    }
    
    .header p {
      font-size: 1.2rem;
    }
    
    article {
      padding: 2rem 1.5rem;
    }
    
    .image-grid {
      grid-template-columns: 1fr;
    }
  }