:root {
    --primary: #0D47A1;
    --secondary: #F5F5F5;
    --accent: #FF9800;
    --text: #333333;
    --light: #FFFFFF;
    --dark: #212121;
  }

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

  body {
    font-family: 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text);
    background: linear-gradient(135deg, var(--secondary), var(--light));
    padding: 0;
    margin: 0;
    overflow-x: hidden;
  }

  .header {
    background: rgba(255,255,255,0.9);
    backdrop-filter: blur(10px);
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    box-shadow: 0 2px 20px rgba(0,0,0,0.1);
    padding: 1rem 5%;
    display: flex;
    justify-content: space-between;
    align-items: center;
  }

  .logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary);
    text-decoration: none;
    display: flex;
    align-items: center;
  }

  .logo span {
    color: var(--accent);
  }

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

  .nav a {
    color: var(--dark);
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    position: relative;
    padding: 0.5rem 0;
  }

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

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

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

  .hero {
    min-height: 80vh;
    display: flex;
    align-items: center;
    padding: 10% 5%;
    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;
    z-index: -1;
  }

  .hero-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
  }

  .hero h1 {
    font-size: 3.5rem;
    margin-bottom: 1.5rem;
    color: var(--primary);
    line-height: 1.2;
  }

  .hero p {
    font-size: 1.2rem;
    margin-bottom: 2rem;
    color: var(--dark);
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
  }

  .notice {
    background: var(--accent);
    color: white;
    padding: 1rem;
    border-radius: 8px;
    margin: 2rem auto;
    max-width: 600px;
    text-align: center;
    font-weight: 500;
    box-shadow: 0 4px 12px rgba(255,152,0,0.3);
  }

  .container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 5rem 5%;
  }

  article {
    background: white;
    border-radius: 16px;
    padding: 3rem;
    box-shadow: 0 10px 30px rgba(0,0,0,0.05);
    margin-bottom: 5rem;
  }

  article h2 {
    font-size: 2.5rem;
    color: var(--primary);
    margin-bottom: 2rem;
    position: relative;
    padding-bottom: 1rem;
  }

  article h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    border-radius: 2px;
  }

  article h3 {
    font-size: 1.8rem;
    color: var(--primary);
    margin: 2rem 0 1.5rem;
  }

  article p {
    font-size: 1.1rem;
    line-height: 1.8;
    margin-bottom: 1.5rem;
    color: var(--dark);
  }

  pre {
    background: #f8f9fa;
    border-radius: 8px;
    padding: 1.5rem;
    margin: 2rem 0;
    overflow: auto;
    border-left: 4px solid var(--accent);
    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;
    font-size: 0.9rem;
    color: var(--primary);
  }

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

  .gallery img {
    width: 100%;
    height: auto;
    border-radius: 12px;
    box-shadow: 0 10px 20px rgba(0,0,0,0.1);
    transition: all 0.3s ease;
  }

  .gallery img:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 30px rgba(0,0,0,0.2);
  }

  .footer {
    background: var(--dark);
    color: white;
    padding: 3rem 5%;
    text-align: center;
  }

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

  .footer-links {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 2rem;
  }

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

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

  @media (max-width: 768px) {
    .hero h1 {
      font-size: 2.5rem;
    }
    
    .nav {
      display: none;
    }
    
    article {
      padding: 2rem;
    }
    
    .gallery {
      grid-template-columns: 1fr;
    }
  }

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

  .fade-in {
    animation: fadeIn 1s ease forwards;
  }

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

  /* Scroll indicator */
  .scroll-indicator {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 50px;
    height: 50px;
    background: var(--primary);
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    color: white;
    font-size: 1.5rem;
    cursor: pointer;
    opacity: 0;
    transition: all 0.3s ease;
    z-index: 100;
    box-shadow: 0 4px 15px rgba(13, 71, 161, 0.3);
  }

  .scroll-indicator.visible {
    opacity: 1;
  }

  .scroll-indicator:hover {
    background: var(--accent);
    transform: translateY(-5px);
  }