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

  body {
    font-family: 'Inter', sans-serif;
    color: #333;
    background: linear-gradient(135deg, #e0f7fa, #f4f6f9, #e3f2fd, #f1f8e9);
    background-size: 400% 400%;
    animation: gradientMove 20s ease infinite;
    transition: background-color 0.5s, color 0.5s;
  }
  @keyframes gradientMove {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
  }

  #particles {
    position: fixed;
    top: 0; left: 0;
    width: 100%; height: 100%;
    z-index: -1;
  }

  .site-header {
    text-align: center;
    padding: 20px;
    background: rgba(255, 255, 255, 0.75);
    backdrop-filter: blur(8px);
    border-bottom: 1px solid rgba(0,0,0,0.1);
    border-radius: 0 0 15px 15px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  }
  .site-header h1 { font-weight: 700; font-size: 1.8rem; }
  .subtitle { font-weight: 500; font-size: 1rem; }

  .glass-card {
    background: rgba(255, 255, 255, 0.8);
    border-radius: 15px;
    padding: 20px;
    margin-bottom: 20px;
    box-shadow: 0px 6px 20px rgba(0,0,0,0.1);
    backdrop-filter: blur(12px);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
  }
  .glass-card:hover { transform: translateY(-5px); box-shadow: 0px 12px 30px rgba(0,0,0,0.15); }

  .button-group a {
    display: inline-block;
    padding: 10px 15px;
    margin: 5px;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    transition: 0.3s ease;
    font-size: 0.9rem;
  }
  .ui-btn { background: #0288d1; color: #fff; }
  .ui-btn:hover { background: #0277bd; transform: scale(1.05); }
  .ui-btn.alt { background: #43a047; color: #fff; }
  .ui-btn.alt:hover { background: #388e3c; transform: scale(1.05); }

  .site-footer {
    text-align: center;
    padding: 15px;
    background: rgba(255, 255, 255, 0.7);
    backdrop-filter: blur(6px);
    border-top: 1px solid rgba(0,0,0,0.1);
    border-radius: 15px 15px 0 0;
    font-size: 0.9rem;
  }

  main { max-width: 900px; margin: auto; padding: 20px; }

  h2, h3 {
    position: relative;
    padding-bottom: 8px;
    margin-bottom: 15px;
    font-size: 1.4rem;
  }
  h2::after, h3::after {
    content: "";
    position: absolute;
    bottom: 0; left: 0;
    width: 60px; height: 3px;
    background: linear-gradient(90deg, #00e5ff, #00ff9d);
    border-radius: 2px;
    transition: width 0.3s ease;
  }
  h2:hover::after, h3:hover::after { width: 100px; }

  /* Dark Mode */
  body.dark {
    background: linear-gradient(135deg, #0d1b2a, #1b263b);
    color: #f0f0f0;
  }
  body.dark .site-header,
  body.dark .glass-card,
  body.dark .site-footer {
    background: rgba(20, 20, 30, 0.85);
  }
  body.dark h2::after, body.dark h3::after {
    background: linear-gradient(90deg, #66fcf1, #45a29e);
    box-shadow: 0 0 8px #66fcf1;
  }

  /* Toggle Button */
  .toggle-wrapper {
    position: fixed;
    top: 20px; right: 20px;
    z-index: 1000;
  }
  .theme-toggle {
    background: none;
    border: none;
    cursor: pointer;
    outline: none;
  }
  .theme-icon { width: 40px; height: 40px; }

  /* Responsive Design */
  @media (max-width: 768px) {
    main { padding: 15px; }
    .glass-card { padding: 15px; }
    .site-header h1 { font-size: 1.5rem; }
    h2, h3 { font-size: 1.2rem; }
    .button-group a { font-size: 0.85rem; padding: 8px 12px; }
  }

  @media (max-width: 480px) {
    .site-header { padding: 15px; }
    .site-header h1 { font-size: 1.2rem; }
    .subtitle { font-size: 0.85rem; }
    main { padding: 10px; }
    .glass-card { padding: 12px; }
    h2, h3 { font-size: 1rem; }
    .site-footer { font-size: 0.8rem; padding: 10px; }
    .theme-icon { width: 32px; height: 32px; }
  }