:root {
    --primary: #0d47a1;
    --secondary: #f5f5f5;
    --accent: #ff9800;
    --text: #333;
    --light: #fff;
    --dark: #222;
    --gray: #777;
    --space: 2rem;
    --radius: 8px;
    --shadow: 0 4px 12px rgba(0,0,0,0.1);
    --transition: all 0.3s ease;
  }

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

  body {
    font-family: 'Segoe UI', system-ui, sans-serif;
    line-height: 1.6;
    color: var(--text);
    background: linear-gradient(135deg, #f9f9f9 0%, #eef2f5 100%);
    padding-top: 80px;
  }

  .header {
    position: fixed;
    top: 0;
    width: 100%;
    background: linear-gradient(to right, var(--primary), #1565c0);
    color: var(--light);
    padding: 1rem 2rem;
    box-shadow: var(--shadow);
    z-index: 1000;
    display: flex;
    justify-content: space-between;
    align-items: center;
  }

  .logo {
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: 1px;
    text-shadow: 0 2px 4px rgba(0,0,0,0.2);
  }

  .nav {
    display: flex;
    gap: 2rem;
  }

  .nav a {
    color: var(--light);
    text-decoration: none;
    font-weight: 500;
    padding: 0.5rem 1rem;
    border-radius: var(--radius);
    transition: var(--transition);
  }

  .nav a:hover {
    background: rgba(255,255,255,0.2);
  }

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

  .hero {
    background: linear-gradient(rgba(13, 71, 161, 0.8), rgba(13, 71, 161, 0.6)), url('https://images.gptkong.com/demo/sample1.png');
    background-size: cover;
    background-position: center;
    color: var(--light);
    padding: 4rem 2rem;
    border-radius: var(--radius);
    margin-bottom: 3rem;
    text-align: center;
    box-shadow: var(--shadow);
  }

  .hero h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    text-shadow: 0 2px 4px rgba(0,0,0,0.3);
  }

  .hero p {
    font-size: 1.2rem;
    max-width: 800px;
    margin: 0 auto 2rem;
  }

  .notice {
    background: var(--light);
    padding: 1rem;
    border-radius: var(--radius);
    margin: 2rem 0;
    text-align: center;
    font-size: 0.9rem;
    color: var(--gray);
    box-shadow: var(--shadow);
  }

  article {
    background: var(--light);
    padding: 2rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    margin-bottom: 3rem;
  }

  article h2 {
    color: var(--primary);
    font-size: 1.8rem;
    margin-bottom: 1.5rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--secondary);
  }

  article h3 {
    color: var(--primary);
    font-size: 1.4rem;
    margin: 2rem 0 1rem;
  }

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

  .image-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin: 2rem 0;
  }

  .image-card {
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: var(--transition);
  }

  .image-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 16px rgba(0,0,0,0.15);
  }

  .image-card img {
    width: 100%;
    height: auto;
    display: block;
  }

  pre {
    background: #2d2d2d;
    color: #f8f8f2;
    padding: 1.5rem;
    border-radius: var(--radius);
    overflow-x: auto;
    margin: 1.5rem 0;
    font-family: 'Courier New', monospace;
    font-size: 0.95rem;
    line-height: 1.5;
  }

  code {
    font-family: 'Courier New', monospace;
    background: rgba(13, 71, 161, 0.1);
    padding: 0.2rem 0.4rem;
    border-radius: 4px;
    color: var(--primary);
    font-size: 0.9rem;
  }

  .footer {
    background: var(--dark);
    color: var(--light);
    padding: 2rem;
    text-align: center;
    margin-top: 3rem;
  }

  .footer p {
    margin-bottom: 1rem;
  }

  .footer-links {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    margin-bottom: 1.5rem;
  }

  .footer-links a {
    color: var(--light);
    text-decoration: none;
    transition: var(--transition);
  }

  .footer-links a:hover {
    color: var(--accent);
  }

  @media (max-width: 768px) {
    .nav {
      display: none;
    }
    
    .hero h1 {
      font-size: 2rem;
    }
    
    .container {
      padding: 1rem;
    }
  }

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

  .animate {
    animation: fadeIn 0.8s ease forwards;
  }

  .delay-1 { animation-delay: 0.2s; }
  .delay-2 { animation-delay: 0.4s; }
  .delay-3 { animation-delay: 0.6s; }