:root {
      --primary: #4a90e2;
      --secondary: #50c878;
      --accent: #f5a623;
      --dark: #2c3e50;
      --light: #f8f9fa;
      --text: #333;
    }

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

    body {
      font-family: 'Roboto', sans-serif;
      background-color: var(--light);
      color: var(--text);
      line-height: 1.6;
      padding: 20px;
    }

    header {
      text-align: center;
      margin-bottom: 30px;
      color: var(--dark);
    }

    main {
      display: grid;
      grid-template-columns: 1fr 3fr;
      gap: 2rem;
      max-width: 1200px;
      margin: 0 auto;
    }

    nav#toc {
      background: var(--dark);
      color: white;
      padding: 20px;
      border-radius: 10px;
      position: sticky;
      top: 20px;
      height: fit-content;
      box-shadow: 0 4px 10px rgba(0,0,0,0.1);
    }

    nav h2 {
      margin-bottom: 15px;
      font-size: 1.5rem;
      text-align: center;
      color: var(--secondary);
    }

    nav h3 {
      margin-bottom: 15px;
      font-size: 1.5rem;
      text-align: center;
      color: var(--secondary);
    }
    nav ul {
      list-style: none;
      padding: 0;
    }

    nav li {
      margin-bottom: 10px;
    }

    nav a {
      color: var(--secondary);
      text-decoration: none;
      font-weight: 500;
      transition: all 0.3s ease;
      display: block;
      padding: 8px 12px;
      border-radius: 6px;
      background: rgba(255,255,255,0.1);
    }

    nav a:hover {
      background: var(--accent);
      color: white;
      transform: translateX(5px);
    }

    nav a.active {
      background: var(--primary);
      color: white;
      font-weight: 600;
    }

    .content {
      background: white;
      padding: 30px;
      border-radius: 10px;
      box-shadow: 0 4px 15px rgba(0,0,0,0.08);
    }

    .section {
      margin-bottom: 40px;
      padding-bottom: 20px;
      border-bottom: 1px dashed #ddd;
    }

    .section h2 {
      color: var(--primary);
      margin-bottom: 15px;
      font-size: 1.8rem;
      border-bottom: 3px solid var(--secondary);
      padding-bottom: 5px;
    }

    .section p {
      margin-bottom: 15px;
      font-size: 1.1rem;
    }

    @media (max-width: 768px) {
      main {
        grid-template-columns: 1fr;
      }

      nav#toc {
        position: static;
        margin-bottom: 20px;
      }

      nav a {
        font-size: 0.9rem;
        padding: 6px 10px;
      }
    }