:root {
    --primary-color: #2C3E50;
    --secondary-color: #8E44AD;
    --accent-color: #3498DB;
    --success-color: #27AE60;
    --error-color: #E74C3C;
    --text-color: #333;
    --light-bg: #f9f9f9;
    --card-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
  }

  * {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Montserrat', 'Open Sans', sans-serif;
  }

  body {
    background-color: var(--light-bg);
    color: var(--text-color);
    line-height: 1.6;
    overflow-x: hidden;
  }

  .container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
  }

  /* Header Styles */
  header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 60px 0;
    position: relative;
    overflow: hidden;
  }

  header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url('https://images.gptkong.com/demo/sample1.png') center/cover no-repeat;
    opacity: 0.1;
    z-index: 0;
  }

  .header-content {
    position: relative;
    z-index: 1;
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
  }

  .header-content h1 {
    font-size: 2.8rem;
    margin-bottom: 20px;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
  }

  .header-content p {
    font-size: 1.2rem;
    margin-bottom: 30px;
  }

  .notice {
    background-color: rgba(255, 255, 255, 0.2);
    padding: 15px;
    border-radius: 8px;
    margin-top: 30px;
    font-size: 0.9rem;
  }

  /* Navigation */
  .navbar {
    position: sticky;
    top: 0;
    background-color: var(--primary-color);
    padding: 15px 0;
    z-index: 1000;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  }

  .nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
  }

  .nav-logo {
    color: white;
    font-weight: bold;
    font-size: 1.5rem;
    text-decoration: none;
  }

  .nav-links {
    display: flex;
    gap: 30px;
  }

  .nav-links a {
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    position: relative;
  }

  .nav-links a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--accent-color);
    transition: var(--transition);
  }

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

  .hamburger {
    display: none;
    cursor: pointer;
  }

  /* Main Content */
  main {
    padding: 60px 0;
  }

  article {
    background-color: white;
    border-radius: 12px;
    box-shadow: var(--card-shadow);
    padding: 40px;
    margin-bottom: 40px;
  }

  article h2 {
    color: var(--primary-color);
    margin-bottom: 30px;
    font-size: 2rem;
    position: relative;
    padding-bottom: 15px;
  }

  article h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 80px;
    height: 4px;
    background: linear-gradient(to right, var(--secondary-color), var(--accent-color));
    border-radius: 2px;
  }

  article h3 {
    color: var(--secondary-color);
    margin: 30px 0 20px;
    font-size: 1.5rem;
  }

  article p {
    margin-bottom: 20px;
    font-size: 1.1rem;
  }

  /* Code Blocks */
  pre {
    background-color: #f5f5f5;
    border-radius: 8px;
    padding: 20px;
    margin: 25px 0;
    overflow: auto;
    border-left: 4px solid var(--accent-color);
  }

  code {
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    color: #333;
  }

  /* Tables */
  table {
    width: 100%;
    border-collapse: collapse;
    margin: 25px 0;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.1);
  }

  th, td {
    padding: 15px;
    text-align: left;
    border-bottom: 1px solid #ddd;
  }

  th {
    background-color: var(--primary-color);
    color: white;
  }

  tr:hover {
    background-color: #f5f5f5;
  }

  /* Image Gallery */
  .gallery {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 20px;
    margin: 40px 0;
  }

  .gallery-item {
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
    transition: var(--transition);
  }

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

  .gallery-item img {
    width: 100%;
    height: auto;
    display: block;
    transition: var(--transition);
  }

  .gallery-item:hover img {
    transform: scale(1.05);
  }

  /* Footer */
  footer {
    background-color: var(--primary-color);
    color: white;
    padding: 40px 0;
    text-align: center;
  }

  .footer-content {
    max-width: 800px;
    margin: 0 auto;
  }

  .footer-links {
    display: flex;
    justify-content: center;
    gap: 30px;
    margin: 20px 0;
  }

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

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

  /* Responsive Design */
  @media (max-width: 768px) {
    .header-content h1 {
      font-size: 2.2rem;
    }

    .nav-links {
      display: none;
    }

    .hamburger {
      display: block;
    }

    article {
      padding: 30px;
    }

    .gallery {
      grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    }
  }

  @media (max-width: 480px) {
    .header-content h1 {
      font-size: 1.8rem;
    }

    article {
      padding: 20px;
    }

    .footer-links {
      flex-direction: column;
      gap: 15px;
    }
  }

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

  .fade-in {
    animation: fadeIn 0.8s ease forwards;
  }

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

  /* Utility Classes */
  .text-center { text-align: center; }
  .mt-20 { margin-top: 20px; }
  .mb-20 { margin-bottom: 20px; }
  .py-40 { padding: 40px 0; }