:root {
    --primary: #0d1b2a;
    --secondary: #1b263b;
    --accent: #00d2ff;
    --highlight: #39ff14;
    --text: #ffffff;
    --neutral: #e0e1dd;
    --card-bg: #16222A;
    --radius: 12px;
    --shadow: 0 8px 24px rgba(0, 0, 0, 0.2);
    --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', system-ui, -apple-system, sans-serif;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: var(--text);
    line-height: 1.6;
    min-height: 100%;
    overflow-x: hidden;
  }

  .container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
  }

  .header {
    text-align: center;
    margin-bottom: 3rem;
    position: relative;
    padding: 2rem 0;
  }

  .header::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 200px;
    height: 3px;
    background: linear-gradient(90deg, transparent, var(--accent), transparent);
    border-radius: 3px;
  }

  h1, h2, h3, h4 {
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: 1.5rem;
    color: var(--neutral);
  }

  h1 {
    font-size: 2.5rem;
    background: linear-gradient(90deg, var(--accent), var(--highlight));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
  }

  h2 {
    font-size: 1.8rem;
    position: relative;
    padding-bottom: 0.5rem;
  }

  h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 60px;
    height: 2px;
    background: var(--accent);
  }

  h3 {
    font-size: 1.4rem;
    color: var(--accent);
  }

  p {
    margin-bottom: 1.5rem;
    font-size: 1.1rem;
  }

  .note {
    background: rgba(0, 210, 255, 0.1);
    border-left: 3px solid var(--accent);
    padding: 1rem;
    margin: 2rem 0;
    border-radius: 0 var(--radius) var(--radius) 0;
  }

  .grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(500px, 1fr));
    gap: 2rem;
    margin: 3rem 0;
  }

  .card {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 2rem;
    box-shadow: var(--shadow);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
  }

  .card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: linear-gradient(90deg, var(--accent), var(--highlight));
  }

  .card:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 28px rgba(0, 0, 0, 0.3);
  }

  .image-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin: 2rem 0;
  }

  .decor-image {
    border-radius: var(--radius);
    width: 100%;
    height: auto;
    object-fit: cover;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
    transition: var(--transition);
    aspect-ratio: 1/1;
  }

  .decor-image:hover {
    transform: scale(1.03);
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.3);
  }

  pre {
    background: rgba(13, 27, 42, 0.8);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin: 2rem 0;
    overflow-x: auto;
    position: relative;
    border: 1px solid rgba(0, 210, 255, 0.2);
  }

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

  code {
    font-family: 'Fira Code', monospace;
    color: var(--highlight);
    font-size: 0.9rem;
  }

  .nav-links {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 1rem;
    margin: 2rem 0;
  }

  .nav-link {
    color: var(--text);
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: 20px;
    background: rgba(0, 210, 255, 0.1);
    border: 1px solid var(--accent);
    transition: var(--transition);
  }

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

  .footer {
    text-align: center;
    margin-top: 4rem;
    padding: 2rem 0;
    border-top: 1px solid rgba(0, 210, 255, 0.2);
  }

  @media (max-width: 768px) {
    .grid {
      grid-template-columns: 1fr;
    }
    
    h1 {
      font-size: 2rem;
    }
    
    h2 {
      font-size: 1.5rem;
    }
  }

  /* Particles animation */
  .particles {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    overflow: hidden;
  }

  .particle {
    position: absolute;
    background: var(--accent);
    border-radius: 50%;
    opacity: 0.3;
    animation: float 15s infinite linear;
  }

  @keyframes float {
    0% {
      transform: translateY(0) translateX(0);
      opacity: 0;
    }
    50% {
      opacity: 0.3;
    }
    100% {
      transform: translateY(-100vh) translateX(100px);
      opacity: 0;
    }
  }

  /* Theme toggle */
  .theme-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 100;
    background: rgba(0, 210, 255, 0.1);
    border: 1px solid var(--accent);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition);
  }

  .theme-toggle:hover {
    background: var(--accent);
  }

  .theme-toggle i {
    color: var(--text);
    font-size: 1.2rem;
  }