:root {
    --primary: #1e3c72;
    --secondary: #2a5298;
    --accent: #ff7e5f;
    --text: #ffffff;
    --light: rgba(255,255,255,0.1);
    --dark: rgba(0,0,0,0.2);
    --radius: 12px;
    --shadow: 0 10px 30px rgba(0,0,0,0.2);
  }

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

  body {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: var(--text);
    font-family: 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    min-height: 100%;
    padding: 0;
    overflow-x: hidden;
  }

  .container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 40px 20px;
  }

  .header {
    position: relative;
    padding: 60px 0;
    text-align: center;
    background: linear-gradient(rgba(30, 60, 114, 0.8), rgba(42, 82, 152, 0.8)), 
                url('https://images.gptkong.com/demo/sample1.png') center/cover;
    border-radius: var(--radius);
    margin-bottom: 60px;
    overflow: hidden;
  }

  .header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(255,255,255,0.1);
    backdrop-filter: blur(8px);
    z-index: 1;
  }

  .header-content {
    position: relative;
    z-index: 2;
    padding: 40px;
  }

  h1, h2, h3, h4 {
    font-weight: 600;
    margin-bottom: 20px;
    line-height: 1.3;
  }

  h1 {
    font-size: 2.8rem;
    background: linear-gradient(90deg, #ffffff, #feb47b);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    margin-bottom: 15px;
  }

  h2 {
    font-size: 2rem;
    color: var(--text);
    border-bottom: 2px solid var(--accent);
    display: inline-block;
    padding-bottom: 5px;
    margin-top: 50px;
  }

  h3 {
    font-size: 1.5rem;
    color: var(--text);
    margin-top: 40px;
  }

  p {
    font-size: 1.1rem;
    margin-bottom: 25px;
    color: rgba(255,255,255,0.9);
  }

  .note {
    background: rgba(255,255,255,0.1);
    padding: 20px;
    border-radius: var(--radius);
    margin: 30px 0;
    border-left: 4px solid var(--accent);
  }

  .note p {
    margin-bottom: 0;
  }

  .grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(500px, 1fr));
    gap: 30px;
    margin: 40px 0;
  }

  .card {
    background: rgba(255,255,255,0.1);
    border-radius: var(--radius);
    padding: 30px;
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
  }

  .card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 35px rgba(0,0,0,0.3);
  }

  .card-img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    border-radius: var(--radius);
    margin-bottom: 20px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    transition: transform 0.3s ease;
  }

  .card-img:hover {
    transform: scale(1.03);
  }

  pre {
    background: rgba(0,0,0,0.3);
    border-radius: var(--radius);
    padding: 20px;
    margin: 30px 0;
    overflow: auto;
    font-size: 0.9rem;
    line-height: 1.5;
    border-left: 4px solid var(--accent);
  }

  code {
    font-family: 'Courier New', monospace;
    color: #feb47b;
  }

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

  .gallery-item {
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: transform 0.3s ease;
  }

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

  .gallery-img {
    width: 100%;
    height: 200px;
    object-fit: cover;
  }

  .nav {
    position: sticky;
    top: 0;
    background: rgba(30, 60, 114, 0.9);
    backdrop-filter: blur(10px);
    padding: 15px 0;
    z-index: 100;
    box-shadow: 0 5px 20px rgba(0,0,0,0.2);
  }

  .nav-list {
    display: flex;
    justify-content: center;
    list-style: none;
    gap: 30px;
  }

  .nav-link {
    color: var(--text);
    text-decoration: none;
    font-weight: 500;
    padding: 10px 15px;
    border-radius: 5px;
    transition: all 0.3s ease;
    position: relative;
  }

  .nav-link:hover {
    color: var(--accent);
  }

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

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

  .footer {
    text-align: center;
    padding: 30px 0;
    margin-top: 60px;
    background: rgba(0,0,0,0.2);
    border-radius: var(--radius);
  }

  @media (max-width: 768px) {
    .grid {
      grid-template-columns: 1fr;
    }
    
    h1 {
      font-size: 2rem;
    }
    
    h2 {
      font-size: 1.5rem;
    }
    
    .header {
      padding: 40px 0;
    }
    
    .nav-list {
      flex-wrap: wrap;
      gap: 15px;
    }
  }

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

  .animate {
    animation: fadeIn 1s ease-out forwards;
  }

  .delay-1 {
    animation-delay: 0.2s;
  }

  .delay-2 {
    animation-delay: 0.4s;
  }

  .delay-3 {
    animation-delay: 0.6s;
  }