:root {
  --bg: #f4f6f8;
  --surface: #ffffff;
  --surface-2: #f0f3f5;
  --text: #14242b;
  --muted: #5d6f78;
  --border: #e2e8ec;
  --accent: #0f766e;
  --accent-2: #14b8a6;
  --accent-soft: #d8f3ee;
  --good: #16a34a;
  --good-soft: #dcfce7;
  --bad: #dc2626;
  --bad-soft: #fde4e4;
  --shadow: 0 6px 24px rgba(16, 42, 50, .08);
  --shadow-sm: 0 2px 8px rgba(16, 42, 50, .06);
  --radius: 18px;
  --radius-sm: 12px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0c1417;
    --surface: #14222a;
    --surface-2: #1b2d36;
    --text: #e7eef1;
    --muted: #9fb2bb;
    --border: #243843;
    --accent: #2dd4bf;
    --accent-2: #14b8a6;
    --accent-soft: #123a37;
    --good: #4ade80;
    --good-soft: #11331f;
    --bad: #f87171;
    --bad-soft: #3a1717;
    --shadow: 0 8px 30px rgba(0, 0, 0, .4);
    --shadow-sm: 0 2px 10px rgba(0, 0, 0, .3);
  }
}

* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  padding-bottom: env(safe-area-inset-bottom);
}

/* ---------- Top bar ---------- */
.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 12px 16px;
  padding-top: calc(12px + env(safe-area-inset-top));
  background: color-mix(in srgb, var(--surface) 85%, transparent);
  backdrop-filter: saturate(160%) blur(12px);
  -webkit-backdrop-filter: saturate(160%) blur(12px);
  border-bottom: 1px solid var(--border);
}
.brand {
  font-weight: 800;
  font-size: 1.12rem;
  letter-spacing: -.02em;
  color: var(--text);
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 8px;
}
.brand-dot { font-size: 1.2rem; }
/* hamburger button (mobile only) */
.hamburger {
  display: inline-flex;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 42px; height: 42px;
  padding: 0 10px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 12px;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}
.hamburger span {
  display: block; height: 2px; width: 100%;
  background: var(--text); border-radius: 2px;
  transition: transform .22s ease, opacity .18s ease;
}
.hamburger[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.hamburger[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.hamburger[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* nav: mobile = dropdown panel under the bar */
.nav {
  position: absolute;
  top: calc(100% + 8px);
  right: 12px;
  left: 12px;
  display: none;
  flex-direction: column;
  gap: 4px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: var(--shadow);
  padding: 8px;
}
.nav.open { display: flex; animation: fade .16s ease; }

.nav-link {
  text-decoration: none;
  color: var(--text);
  font-weight: 650;
  font-size: 1rem;
  padding: 12px 16px;
  border-radius: 12px;
  transition: background .15s, color .15s;
}
.nav-link:active { background: var(--surface-2); }
.nav-link.active { background: var(--accent-soft); color: var(--accent); }

.nav-backdrop {
  position: fixed; inset: 0;
  z-index: 15;
  background: transparent;
}

/* desktop: inline pill segmented nav, no hamburger */
@media (min-width: 600px) {
  .hamburger, .nav-backdrop { display: none !important; }
  .nav {
    position: static;
    display: flex;
    flex-direction: row;
    gap: 6px;
    background: var(--surface-2);
    border: none;
    box-shadow: none;
    border-radius: 999px;
    padding: 4px;
  }
  .nav-link {
    color: var(--muted);
    font-weight: 600;
    font-size: .92rem;
    padding: 7px 16px;
    border-radius: 999px;
  }
  .nav-link.active { background: var(--surface); color: var(--accent); box-shadow: var(--shadow-sm); }
}

/* ---------- Layout ---------- */
.view { max-width: 680px; margin: 0 auto; padding: 20px 16px 64px; }

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 22px;
}

/* ---------- Quiz header ---------- */
.quiz-head { display: flex; flex-direction: column; gap: 12px; margin-bottom: 18px; }
.quiz-meta { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.pill {
  font-size: .78rem;
  font-weight: 700;
  letter-spacing: .04em;
  text-transform: uppercase;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 5px 12px;
  border-radius: 999px;
}
.counter { font-size: .9rem; font-weight: 700; color: var(--muted); }
.counter b { color: var(--text); }

.progress { height: 8px; background: var(--surface-2); border-radius: 999px; overflow: hidden; }
.progress > span {
  display: block; height: 100%;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  border-radius: 999px;
  transition: width .35s cubic-bezier(.4, 0, .2, 1);
}

/* ---------- Question ---------- */
.question {
  font-size: 1.28rem;
  font-weight: 750;
  letter-spacing: -.01em;
  margin: 6px 0 20px;
}
@media (max-width: 480px) { .question { font-size: 1.14rem; } }

.answers { display: grid; gap: 12px; }
.answer {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  width: 100%;
  text-align: left;
  font: inherit;
  font-size: 1.02rem;
  color: var(--text);
  background: var(--surface);
  border: 2px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 15px 16px;
  cursor: pointer;
  transition: transform .08s, border-color .15s, background .15s, box-shadow .15s;
  -webkit-tap-highlight-color: transparent;
}
.answer:hover:not(:disabled) { border-color: var(--accent); box-shadow: var(--shadow-sm); }
.answer:active:not(:disabled) { transform: scale(.99); }
.answer:disabled { cursor: default; }

.answer .key {
  flex: 0 0 auto;
  width: 28px; height: 28px;
  display: grid; place-items: center;
  font-weight: 800; font-size: .9rem;
  border-radius: 8px;
  background: var(--surface-2);
  color: var(--muted);
  transition: background .15s, color .15s;
}
.answer .txt { flex: 1; padding-top: 1px; }
.answer .mark { flex: 0 0 auto; font-weight: 800; opacity: 0; transition: opacity .15s; }

.answer.correct {
  border-color: var(--good);
  background: var(--good-soft);
}
.answer.correct .key { background: var(--good); color: #fff; }
.answer.correct .mark { opacity: 1; color: var(--good); }

.answer.wrong {
  border-color: var(--bad);
  background: var(--bad-soft);
  opacity: .85;
}
.answer.wrong .key { background: var(--bad); color: #fff; }
.answer.wrong .mark { opacity: 1; color: var(--bad); }

/* ---------- Footer / buttons ---------- */
.actions { margin-top: 20px; display: flex; gap: 12px; align-items: center; justify-content: space-between; }
.hint { font-size: .9rem; color: var(--muted); }
.btn {
  font: inherit; font-weight: 700; font-size: 1rem;
  border: none; cursor: pointer;
  padding: 13px 22px; border-radius: 999px;
  transition: transform .08s, filter .15s, background .15s;
  -webkit-tap-highlight-color: transparent;
}
.btn:active { transform: scale(.97); }
.btn-primary { background: linear-gradient(90deg, var(--accent), var(--accent-2)); color: #fff; box-shadow: var(--shadow-sm); }
.btn-primary:hover { filter: brightness(1.05); }
.btn-ghost { background: var(--surface-2); color: var(--text); }
.btn-block { width: 100%; }

/* ---------- Results ---------- */
.result { text-align: center; }
.result .score {
  font-size: 3.4rem; font-weight: 850; letter-spacing: -.03em;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text; background-clip: text; color: transparent;
  line-height: 1.1; margin: 10px 0 4px;
}
.result p { color: var(--muted); margin: 0 0 24px; }
.result .emoji { font-size: 3rem; }

/* ---------- Search ---------- */
.search-wrap { position: relative; margin-bottom: 18px; }
.search-input {
  width: 100%;
  font: inherit; font-size: 1.05rem;
  color: var(--text);
  background: var(--surface);
  border: 2px solid var(--border);
  border-radius: 999px;
  padding: 15px 18px 15px 48px;
  box-shadow: var(--shadow-sm);
  transition: border-color .15s, box-shadow .15s;
}
.search-input:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 4px var(--accent-soft); }
.search-icon { position: absolute; left: 17px; top: 50%; transform: translateY(-50%); color: var(--muted); font-size: 1.1rem; pointer-events: none; }

.search-meta { font-size: .88rem; color: var(--muted); margin: 0 4px 14px; }

.result-item { margin-bottom: 14px; }
.result-item .cat {
  font-size: .72rem; font-weight: 700; letter-spacing: .05em; text-transform: uppercase;
  color: var(--accent);
}
.result-item .q { font-weight: 700; font-size: 1.05rem; margin: 4px 0 12px; }
.opt {
  display: flex; gap: 10px; align-items: flex-start;
  padding: 9px 12px; border-radius: 10px; font-size: .98rem;
  border: 1px solid transparent;
}
.opt + .opt { margin-top: 6px; }
.opt .k { font-weight: 800; color: var(--muted); flex: 0 0 auto; }
.opt.is-correct { background: var(--good-soft); border-color: color-mix(in srgb, var(--good) 35%, transparent); }
.opt.is-correct .k { color: var(--good); }
.opt.is-correct .v { font-weight: 650; }
.opt.is-correct::after { content: "✓"; margin-left: auto; color: var(--good); font-weight: 800; }
.no-answer { font-size: .85rem; color: var(--muted); font-style: italic; margin-top: 8px; }

mark { background: #fde68a; color: inherit; border-radius: 3px; padding: 0 1px; }
@media (prefers-color-scheme: dark) { mark { background: #7c5e12; color: #fff; } }

.empty { text-align: center; color: var(--muted); padding: 48px 16px; }
.empty .emoji { font-size: 2.6rem; display: block; margin-bottom: 8px; }

/* ---------- Questions (all, grouped) ---------- */
.cat-head {
  position: sticky;
  top: calc(58px + env(safe-area-inset-top));
  z-index: 5;
  display: flex; align-items: baseline; gap: 8px;
  margin: 22px -4px 12px;
  padding: 8px 14px;
  font-size: .92rem; font-weight: 800; letter-spacing: .04em; text-transform: uppercase;
  color: var(--accent);
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px);
  border-radius: 10px;
}
.cat-head:first-child { margin-top: 4px; }
.cat-head .count { color: var(--muted); font-weight: 700; font-size: .8rem; letter-spacing: 0; text-transform: none; }
.qlist .result-item .q { font-size: 1.04rem; }

.loader { display: flex; justify-content: center; padding: 18px 0 6px; }
.spinner {
  width: 26px; height: 26px;
  border: 3px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin .7s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }
.end-note { text-align: center; color: var(--muted); font-size: .85rem; padding: 16px 0 0; }

.fade { animation: fade .25s ease; }
@keyframes fade { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }