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

  body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #121212;
    color: #eee;
    line-height: 1.6;
    min-height: 100vh;
    padding-top: 80px;
    transition: background-color 0.5s ease, color 0.5s ease;
  }

  header {
    position: fixed;
    top: 0; left: 0; right: 0;
    background: #222;
    color: #61dafb;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 2rem;
    font-weight: bold;
    font-size: 1.5rem;
    letter-spacing: 2px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.7);
    z-index: 1000;
  }

  main {
    max-width: 900px;
    margin: 0 auto;
    padding: 0 1rem 4rem;
  }

  section {
    background: #282c34;
    border-radius: 12px;
    padding: 2rem;
    margin: 80px 0;
    box-shadow: 0 8px 15px rgba(0,0,0,0.3);
    opacity: 0;
    transform: translateY(40px);
    animation-fill-mode: forwards;
    animation-name: fadeSlideUp;
    animation-duration: 1s;
  }

  section:nth-child(1) { animation-delay: 0.3s; }
  section:nth-child(2) { animation-delay: 0.8s; }
  section:nth-child(3) { animation-delay: 1.3s; }
  section:nth-child(4) { animation-delay: 1.8s; }
  section:nth-child(5) { animation-delay: 2.3s; }
  section:nth-child(6) { animation-delay: 2.8s; }

  @keyframes fadeSlideUp {
    to {
      opacity: 1;
      transform: translateY(0);
    }
  }

  h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    color: #21a1f1;
    text-shadow: 0 0 8px #61dafb66;
  }

  p {
    font-size: 1.125rem;
    color: #ccc;
  }

  ul.features {
    margin-top: 1rem;
    list-style: none;
    padding-left: 1rem;
  }
  ul.features li {
    margin: 0.6rem 0;
    font-size: 1.1rem;
  }
  ul.features li::before {
    content: "✔️";
    margin-right: 0.6rem;
    color: #61dafb;
  }

  blockquote {
    margin: 1.5rem 0;
    padding-left: 1rem;
    border-left: 4px solid #61dafb;
    font-style: italic;
    color: #99caff;
  }


  #toggleBtn {
    background: linear-gradient(45deg, #61dafb, #21a1f1);
    border: none;
    border-radius: 50px;
    padding: 0.5rem 1.8rem;
    font-size: 1rem;
    color: #121212;
    cursor: default; 
    box-shadow: 0 8px 15px rgba(33, 161, 241, 0.5);
    font-weight: 600;
    user-select: none;
    transition: background 0.3s ease, color 0.3s ease, transform 0.2s ease;
  }
  #toggleBtn:hover {
    background: linear-gradient(45deg, #21a1f1, #61dafb);
    transform: scale(1.05);
  }
  #toggleBtn:active {
    transform: scale(0.95);
  }


  footer {
    text-align: center;
    padding: 2rem 1rem;
    font-size: 0.9rem;
    color: #666;
  }
  section:nth-child(odd) {
  background-color: #6c757d; 
  color: #f8f9fa; 
  box-shadow: 0 6px 15px rgba(108,117,125,0.4);
}

section:nth-child(even) {
  background-color: #495057; 
  color: #e9ecef;
  box-shadow: 0 6px 15px rgba(73,80,87,0.6);
}



@media (max-width: 768px) {
  header {
    flex-direction: column;
    align-items: flex-start;
    font-size: 1.2rem;
    padding: 1rem;
    gap: 0.5rem;
  }

  #toggleBtn {
    width: 100%;
    margin-top: 0.5rem;
    font-size: 1rem;
  }

  main {
    padding: 0 1rem;
  }

  section {
    margin: 40px 0;
    padding: 1rem;
  }

  h2 {
    font-size: 1.8rem;
  }

  p,
  ul.features li,
  blockquote {
    font-size: 1rem;
  }
}


@media (max-width: 480px) {
  body {
    padding-top: 90px;
    padding-left: 0.5rem;
    padding-right: 0.5rem;
  }

  header {
    font-size: 1rem;
    padding: 0.8rem;
    gap: 0.4rem;
  }

  #toggleBtn {
    padding: 0.6rem;
    font-size: 0.9rem;
    width: 100%;
  }

  main {
    padding: 0;
  }

  section {
    padding: 0.8rem;
    margin: 30px 0;
  }

  h2 {
    font-size: 1.5rem;
  }

  p,
  ul.features li,
  blockquote {
    font-size: 0.95rem;
  }

  footer {
    font-size: 0.8rem;
    padding: 1rem;
  }
}