:root {
    --primary: #4A90E2;
    --secondary: #9013FE;
    --accent: #ffa500;
    --light: #f8f9fa;
    --dark: #212529;
    --gray: #6c757d;
    --gradient: linear-gradient(135deg, var(--primary), var(--secondary));
  }

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

  body {
    background-color: var(--light);
    color: var(--dark);
    line-height: 1.6;
    padding-top: 80px;
    overflow-x: hidden;
  }

  .notice {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background: rgba(0,0,0,0.7);
    color: white;
    padding: 10px 15px;
    border-radius: 5px;
    z-index: 1000;
    font-size: 14px;
  }

  header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background: var(--gradient);
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
    z-index: 1000;
    padding: 15px 0;
    transition: all 0.3s ease;
  }

  .nav-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 20px;
  }

  .logo {
    color: white;
    font-size: 1.5rem;
    font-weight: 700;
    text-decoration: none;
  }

  nav ul {
    display: flex;
    list-style: none;
  }

  nav ul li {
    margin-left: 30px;
  }

  nav ul li a {
    color: white;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    position: relative;
  }

  nav ul li a:hover {
    color: var(--accent);
  }

  nav ul li a::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: -5px;
    left: 0;
    background-color: var(--accent);
    transition: width 0.3s ease;
  }

  nav ul li a:hover::after {
    width: 100%;
  }

  .hero {
    height: 500px;
    background: var(--gradient);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    text-align: center;
    position: relative;
    overflow: hidden;
  }

  .hero::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;
  }

  .hero-content {
    max-width: 800px;
    padding: 0 20px;
    z-index: 1;
  }

  .hero h1 {
    font-size: 3rem;
    margin-bottom: 20px;
    animation: fadeIn 1s ease;
  }

  .hero p {
    font-size: 1.2rem;
    margin-bottom: 30px;
    animation: fadeIn 1.5s ease;
  }

  .btn {
    display: inline-block;
    background: var(--accent);
    color: white;
    padding: 12px 30px;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    animation: fadeIn 2s ease;
  }

  .btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 20px rgba(0,0,0,0.1);
  }

  .container {
    max-width: 1200px;
    margin: 50px auto;
    padding: 0 20px;
  }

  article {
    background: white;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
    padding: 40px;
    margin-bottom: 50px;
  }

  article h2 {
    color: var(--primary);
    margin-bottom: 20px;
    font-size: 2rem;
    position: relative;
    padding-bottom: 10px;
  }

  article h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 50px;
    height: 3px;
    background: var(--gradient);
  }

  article p {
    margin-bottom: 20px;
    font-size: 1.1rem;
    line-height: 1.8;
  }

  pre {
    background: #f5f7fa;
    border-radius: 8px;
    padding: 20px;
    margin: 20px 0;
    overflow: auto;
    border-left: 4px solid var(--primary);
  }

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

  .image-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 20px;
    margin: 30px 0;
  }

  .image-card {
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    transition: all 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;
  }

  footer {
    background: var(--dark);
    color: white;
    padding: 50px 0;
    text-align: center;
  }

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

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

  .footer-links a {
    color: white;
    margin: 0 15px;
    text-decoration: none;
    transition: color 0.3s ease;
  }

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

  .copyright {
    opacity: 0.7;
    font-size: 0.9rem;
  }

  @keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
  }

  @media (max-width: 768px) {
    .nav-container {
      flex-direction: column;
    }

    nav ul {
      margin-top: 20px;
    }

    nav ul li {
      margin-left: 15px;
    }

    .hero h1 {
      font-size: 2rem;
    }

    .hero p {
      font-size: 1rem;
    }

    article {
      padding: 20px;
    }

    .image-grid {
      grid-template-columns: 1fr;
    }
  }