:root {
    --primary: #0D47A1;
    --secondary: #BBDEFB;
    --accent: #4CAF50;
    --highlight: #FF9800;
    --text: #333;
    --light: #fff;
    --dark: #222;
    --shadow: 0 4px 20px rgba(0,0,0,0.1);
    --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
  }

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

  body {
    font-family: 'Roboto', sans-serif;
    color: var(--text);
    line-height: 1.6;
    background: linear-gradient(135deg, #f5f7fa 0%, #e4e8eb 100%);
    overflow-x: hidden;
  }

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

  .header-banner {
    position: relative;
    height: 600px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(rgba(13, 71, 161, 0.8), rgba(13, 71, 161, 0.8)), 
                url('https://images.gptkong.com/demo/sample1.png') center/cover;
    color: var(--light);
    text-align: center;
    margin-bottom: 80px;
    clip-path: polygon(0 0, 100% 0, 100% 85%, 0 100%);
  }

  .header-content {
    max-width: 800px;
    padding: 40px;
    position: relative;
    z-index: 2;
  }

  .header-banner h1 {
    font-size: 3.5rem;
    margin-bottom: 20px;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
    animation: fadeInDown 1s ease;
  }

  .header-banner p {
    font-size: 1.2rem;
    margin-bottom: 30px;
    animation: fadeInUp 1s ease 0.3s forwards;
    opacity: 0;
  }

  .notice {
    background: var(--light);
    color: var(--primary);
    padding: 15px;
    border-radius: 8px;
    margin: 20px 0;
    box-shadow: var(--shadow);
    text-align: center;
    font-weight: bold;
  }

  article {
    background: var(--light);
    border-radius: 12px;
    box-shadow: var(--shadow);
    padding: 40px;
    margin-bottom: 60px;
  }

  article h2 {
    color: var(--primary);
    font-size: 2.2rem;
    margin-bottom: 30px;
    position: relative;
    padding-bottom: 15px;
  }

  article h2:after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 80px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    border-radius: 2px;
  }

  article h3 {
    color: var(--primary);
    font-size: 1.8rem;
    margin: 40px 0 20px;
  }

  article p {
    font-size: 1.1rem;
    margin-bottom: 25px;
  }

  .image-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    margin: 40px 0;
  }

  .image-card {
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: var(--transition);
  }

  .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;
  }

  pre {
    background: #282c34;
    color: #abb2bf;
    padding: 20px;
    border-radius: 8px;
    overflow-x: auto;
    margin: 30px 0;
    font-size: 0.95rem;
    line-height: 1.5;
    position: relative;
  }

  pre:before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: linear-gradient(to bottom, var(--primary), var(--accent));
    border-radius: 8px 0 0 8px;
  }

  code {
    font-family: 'Fira Code', monospace;
  }

  .nav-tabs {
    display: flex;
    margin-bottom: 30px;
    border-bottom: 2px solid #eee;
  }

  .nav-tabs a {
    padding: 15px 25px;
    text-decoration: none;
    color: var(--text);
    font-weight: bold;
    position: relative;
    transition: var(--transition);
  }

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

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

  .nav-tabs a:hover:after, .nav-tabs a.active:after {
    width: 100%;
  }

  .btn-gradient {
    background: linear-gradient(45deg, var(--secondary), var(--accent));
    border: none;
    color: var(--light);
    padding: 12px 30px;
    text-align: center;
    text-decoration: none;
    display: inline-block;
    font-size: 1rem;
    margin: 10px 0;
    cursor: pointer;
    border-radius: 50px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    transition: var(--transition);
    font-weight: bold;
  }

  .btn-gradient:hover {
    background: linear-gradient(45deg, var(--accent), var(--secondary));
    box-shadow: 0 8px 25px rgba(0,0,0,0.2);
    transform: translateY(-3px);
  }

  @keyframes fadeInDown {
    from {
      opacity: 0;
      transform: translateY(-30px);
    }
    to {
      opacity: 1;
      transform: translateY(0);
    }
  }

  @keyframes fadeInUp {
    from {
      opacity: 0;
      transform: translateY(30px);
    }
    to {
      opacity: 1;
      transform: translateY(0);
    }
  }

  @media (max-width: 768px) {
    .header-banner {
      height: 500px;
    }
    
    .header-banner h1 {
      font-size: 2.5rem;
    }
    
    article {
      padding: 30px 20px;
    }
    
    article h2 {
      font-size: 1.8rem;
    }
    
    article h3 {
      font-size: 1.5rem;
    }
  }