:root {
    --bg: #0f1226;
    --panel: #14183a;
    --text: #e8e8ff;
    --muted: #b6b9ff;
    --brand: #7c4dff;   /* neon purple */
    --brand-2: #00e5ff; /* neon cyan */
    --accent: #ff6ec7;  /* pink */
    --ok: #22c55e;
    --warn: #f59e0b;
    --shadow: 0 10px 25px rgba(0,0,0,.35);
  }

  /* Light theme override */
  :root.light {
    --bg: #f7f7ff;
    --panel: #ffffff;
    --text: #111229;
    --muted: #4e4f7a;
    --shadow: 0 10px 25px rgba(15,18,38,.12);
  }

  * { box-sizing: border-box; }
  html, body { height: 100%; }
  body {
    margin: 0;
    font-family: "Poppins", system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
    color: var(--text);
    background: radial-gradient(600px 400px at -3% 70%, rgba(124, 77, 255, .25), transparent 50%), 
                radial-gradient(500px 300px at 110% 31%, rgba(0, 229, 255, .25), transparent 50%), 
                var(--bg);
    overflow-x: hidden;
  }

  /* ======= Global UI ======= */
  .container { width: min(1120px, 92%); margin: 0 auto; }
  .pill { padding: 8px 14px; border-radius: 999px; font-weight: 600; display: inline-flex; align-items: center; gap: 8px; }
  .btn {
    --c1: var(--brand);
    --c2: var(--brand-2);
    position: relative;
    display: inline-flex; align-items: center; gap: 10px;
    padding: 14px 20px; border-radius: 14px; border: 0; cursor: pointer;
    color: white; font-weight: 700; letter-spacing: .2px;
    background: linear-gradient(135deg, var(--c1), pink);
    box-shadow: 0 8px 18px rgba(124,77,255,.35), 0 2px 6px rgba(0,229,255,.2);
    transition: transform .15s ease, box-shadow .2s ease, opacity .2s ease;
    text-decoration: none;
  }
  .btn:hover { transform: translateY(-2px); box-shadow: 0 12px 24px rgba(124,77,255,.4), 0 6px 18px rgba(0,229,255,.25); }
  .btn:active { transform: translateY(0); }
  .btn--ghost {
    background: transparent; color: var(--text); border: 1.5px dashed rgba(255,255,255,.35);
    box-shadow: none;
  }

  /* ======= Nav ======= */
  .nav {
    position: sticky; top: 0; z-index: 50; backdrop-filter: saturate(160%) blur(10px);
    background: linear-gradient(180deg, rgba(20,24,58,.65), rgba(20,24,58,0));
  }
  .nav__bar { display: flex; justify-content: space-between; align-items: center; padding: 16px 0; }
  .brand { display: flex; align-items: center; gap: 10px; font-family: "Fredoka", sans-serif; font-weight: 700; letter-spacing: .5px; }
  .brand__logo { width: 36px; height: 36px; border-radius: 12px; background: linear-gradient(135deg, var(--brand), var(--accent)); box-shadow: var(--shadow); display: grid; place-items: center; font-weight: 800; }
  .brand__logo span { color: white; }
  .nav__links { display: flex; gap: 18px; align-items: center; }
  .nav__link { color: var(--text); text-decoration: none; font-weight: 600; opacity: .85; }
  .nav__link:hover { opacity: 1; }
  .theme-toggle { border: 0; background: transparent; color: var(--text); font-size: 18px; cursor: pointer; opacity: .85; }

  /* ======= Hero ======= */
  .hero {
    position: relative; isolation: isolate;
    padding: 120px 0 80px;
    text-align: center;
    background-size: cover; background-position: center; color: white;
  }
  .hero__eyebrow { color: white; background: rgba(255,255,255,.15); border: 1px solid rgba(255,255,255,.25); }
  .hero__title { font-family: "Fredoka", sans-serif; font-size: clamp(36px, 6vw, 64px); line-height: 1.05; margin: 16px auto; max-width: 15ch; }
  .hero__subtitle { margin: 0 auto 26px; max-width: 60ch; color: #eef; opacity: .95; }
  .hero__cta { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }

  /* Floating stickers */
  .sticker { position: absolute; z-index: -1; filter: drop-shadow(0 10px 20px rgba(0,0,0,.25)); opacity: .9; }
  .sticker--star { top: 20%; left: 5%; transform: rotate(-10deg); }
  .sticker--bolt { bottom: 8%; right: 8%; transform: rotate(12deg); }

  /* ======= Sections ======= */
  section { padding: 80px 0; }
  .card-grid { display: grid; grid-template-columns: repeat(12, 1fr); gap: 20px; }
  .card { grid-column: span 4; background: linear-gradient(180deg, rgba(255,255,255,.06), rgba(255,255,255,.02)); border: 1px solid rgba(255,255,255,.12); border-radius: 16px; padding: 22px; box-shadow: var(--shadow); backdrop-filter: blur(6px) saturate(140%); }
  .card h3 { margin: 6px 0 10px; font-size: 20px; color: white; }
  .card p { margin: 0; }

  .badge { display: inline-block; font-size: 12px; font-weight: 700; letter-spacing: .3px; text-transform: uppercase; background: linear-gradient(135deg, var(--brand), var(--accent)); color: #fff; padding: 6px 10px; border-radius: 999px; }

  /* About */
  .about__wrap { display: grid; grid-template-columns: 1.1fr 1fr; gap: 28px; align-items: center; }
  .about__img { width: 100%; border-radius: 20px; aspect-ratio: 4/3; object-fit: cover; box-shadow: var(--shadow); }

  /* Topics */
  .topics .card { transition: transform .15s ease; }
  .topics .card:hover { transform: translateY(-4px) rotate(-.3deg); }

  /* FAQ */
  details { background: var(--panel); border-radius: 14px; padding: 16px 18px; border: 1px solid rgba(255,255,255,.1); box-shadow: var(--shadow); }
  details+details { margin-top: 12px; }
  summary { cursor: pointer; font-weight: 700; }

  /* Footer */
  footer { padding: 40px 0 80px; color: var(--muted); text-align: center; }

  /* Responsive */
  @media (max-width: 900px) {
    .card { grid-column: span 6; }
    .t-list { grid-template-columns: 1fr 1fr; }
    .about__wrap { grid-template-columns: 1fr; }
  }
  @media (max-width: 640px) {
    .card { grid-column: span 12; }
    .t-list { grid-template-columns: 1fr; }
    .hero { padding: 96px 0 64px; }
    .nav__links { display: none; }
  }