:root {
    --primary-color: #001f3f;
    --secondary-color: #003f7f;
    --accent-color: #00BFFF;
    --success-color: #32CD32;
    --warning-color: #FFD700;
    --danger-color: #FF4500;
    --light-color: #f8f9fa;
    --dark-color: #212529;
    --text-color: #333;
    --text-light: #f8f9fa;
    --border-radius: 8px;
    --box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
  }

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

  body {
    font-family: 'Open Sans', 'Segoe UI', Roboto, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    background-size: 400% 400%;
    animation: gradientAnimation 15s ease infinite;
    min-height: 100%;
    padding: 2rem 0;
  }

  @keyframes gradientAnimation {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
  }

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

  .header {
    text-align: center;
    margin-bottom: 3rem;
    position: relative;
  }

  .header h1 {
    font-size: 2.5rem;
    color: var(--text-light);
    margin-bottom: 1rem;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
    position: relative;
    display: inline-block;
  }

  .header h1::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 100px;
    height: 3px;
    background: var(--accent-color);
    border-radius: 3px;
  }

  .header p {
    color: rgba(255, 255, 255, 0.8);
    font-size: 1.1rem;
    max-width: 800px;
    margin: 0 auto;
  }

  .reference-banner {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    padding: 15px;
    border-radius: var(--border-radius);
    margin: 2rem auto;
    max-width: 800px;
    text-align: center;
    color: var(--text-light);
    border: 1px solid rgba(255, 255, 255, 0.2);
    box-shadow: var(--box-shadow);
  }

  .content-wrapper {
    display: grid;
    grid-template-columns: 250px 1fr;
    gap: 2rem;
    margin-top: 2rem;
  }

  @media (max-width: 992px) {
    .content-wrapper {
      grid-template-columns: 1fr;
    }
  }

  .sidebar {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    box-shadow: var(--box-shadow);
    border: 1px solid rgba(255, 255, 255, 0.2);
    height: fit-content;
    position: sticky;
    top: 20px;
  }

  .sidebar h3 {
    color: var(--text-light);
    margin-bottom: 1rem;
    font-size: 1.2rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.2);
    padding-bottom: 0.5rem;
  }

  .sidebar ul {
    list-style: none;
  }

  .sidebar li {
    margin-bottom: 0.5rem;
  }

  .sidebar a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    display: block;
    padding: 0.5rem;
    border-radius: 4px;
    transition: var(--transition);
  }

  .sidebar a:hover {
    background: rgba(255, 255, 255, 0.2);
    color: var(--text-light);
  }

  .main-content {
    background: rgba(255, 255, 255, 0.95);
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--box-shadow);
  }

  article {
    max-width: 100%;
    min-width: 500px;
  }

  article h2 {
    font-size: 1.8rem;
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    position: relative;
    padding-bottom: 0.5rem;
  }

  article h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 60px;
    height: 3px;
    background: var(--accent-color);
    border-radius: 3px;
  }

  article h3 {
    font-size: 1.4rem;
    color: var(--secondary-color);
    margin: 2rem 0 1rem;
  }

  article p {
    margin-bottom: 1.5rem;
    font-size: 1.05rem;
    line-height: 1.7;
  }

  article ol {
    margin-bottom: 1.5rem;
    padding-left: 2rem;
  }

  article li {
    margin-bottom: 0.5rem;
  }

  .card {
    background: white;
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin-bottom: 2rem;
    box-shadow: 0 2px 15px rgba(0, 0, 0, 0.1);
    transition: var(--transition);
  }

  .card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.15);
  }

  .image-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    gap: 1rem;
    margin: 2rem 0;
  }

  .image-card {
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
    transition: var(--transition);
    aspect-ratio: 1/1;
  }

  .image-card:hover {
    transform: scale(1.05);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.2);
  }

  .image-card img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
  }

  pre {
    background: #f5f5f5;
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin: 1.5rem 0;
    overflow-x: auto;
    font-family: 'Courier New', Courier, monospace;
    font-size: 0.9rem;
    line-height: 1.5;
    position: relative;
    border-left: 4px solid var(--accent-color);
  }

  pre::before {
    content: 'CSS';
    position: absolute;
    top: 0;
    right: 0;
    background: var(--accent-color);
    color: white;
    padding: 0.2rem 0.8rem;
    font-size: 0.8rem;
    border-radius: 0 0 0 var(--border-radius);
  }

  code {
    font-family: 'Courier New', Courier, monospace;
    background: rgba(0, 191, 255, 0.1);
    padding: 0.2rem 0.4rem;
    border-radius: 3px;
    font-size: 0.9rem;
  }

  .summary {
    background: rgba(0, 191, 255, 0.1);
    border-left: 4px solid var(--accent-color);
    padding: 1.5rem;
    margin: 2rem 0;
    border-radius: 0 var(--border-radius) var(--border-radius) 0;
  }

  .summary h4 {
    color: var(--secondary-color);
    margin-bottom: 0.5rem;
  }

  @media (max-width: 768px) {
    .header h1 {
      font-size: 2rem;
    }
    
    article {
      min-width: 100%;
      padding: 1rem;
    }
    
    article h2 {
      font-size: 1.5rem;
    }
    
    article h3 {
      font-size: 1.2rem;
    }
    
    .image-grid {
      grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    }
  }