:root {
  color-scheme: light dark;
  --bg: #f6f5f1;
  --card: #ffffff;
  --fg: #1d1d1f;
  --sub: #66676b;
  --line: #e3e0d8;
  --btn: #f2f0ea;
  --btn-hover: #e9e6de;
  --accent: #e5530f;
  --accent-fg: #ffffff;
  --good: #17804a;
  --good-bg: #e3f5ea;
  --bad: #c0392b;
  --bad-bg: #fbe9e6;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.05), 0 6px 18px rgba(0, 0, 0, 0.05);
  --radius: 14px;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #101113;
    --card: #1b1c20;
    --fg: #f2f2f4;
    --sub: #9da1a9;
    --line: #2c2e34;
    --btn: #25272d;
    --btn-hover: #2e3138;
    --accent: #ff7b4a;
    --accent-fg: #1a0c04;
    --good: #55d394;
    --good-bg: #12291c;
    --bad: #ff8a80;
    --bad-bg: #2d1716;
    --shadow: none;
  }
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }

html { -webkit-text-size-adjust: 100%; text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", "Helvetica Neue", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  overflow-wrap: anywhere;
}

.wrap {
  max-width: 1100px;
  margin: 0 auto;
  padding: 20px 16px 56px;
}

/* ---------- hero ---------- */
.hero h1 {
  margin: 0 0 6px;
  font-size: 28px;
  line-height: 1.25;
  letter-spacing: 0.5px;
}
.lead {
  margin: 0 0 14px;
  color: var(--sub);
  font-size: 15px;
}
.steps {
  margin: 0 0 10px;
  padding: 0;
  list-style: none;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 8px;
}
.steps li {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 10px 12px;
  font-size: 14px;
}
.steps b { color: var(--accent); }
.rule {
  margin: 0 0 16px;
  color: var(--sub);
  font-size: 14px;
}

@media (min-width: 720px) {
  .steps { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

/* ---------- sticky tabs + score ---------- */
.sticky {
  position: sticky;
  top: 0;
  z-index: 10;
  margin: 0 -16px 16px;
  padding: 10px 16px;
  background: var(--bg);
  border-bottom: 1px solid var(--line);
}
.sticky > * {
  max-width: 1100px;
  margin-left: auto;
  margin-right: auto;
}
.tabs {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
  margin-bottom: 8px;
}
.tab {
  min-height: 44px;
  padding: 6px 10px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--card);
  color: var(--fg);
  font: inherit;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
}
.tab[aria-selected="true"] {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-fg);
}
.toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  font-size: 15px;
}
.score strong {
  font-size: 18px;
  color: var(--accent);
}
.ghost {
  min-height: 40px;
  padding: 6px 14px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--card);
  color: var(--fg);
  font: inherit;
  font-size: 14px;
  cursor: pointer;
}

/* ---------- scene panels ---------- */
.scene-head { margin: 4px 0 14px; }
.scene-head h2 {
  margin: 0 0 4px;
  font-size: 20px;
  line-height: 1.3;
}
.scene-head p {
  margin: 0;
  color: var(--sub);
  font-size: 14px;
}
.scene-head .progress {
  margin-top: 6px;
  color: var(--fg);
  font-weight: 600;
}

.cards {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 16px;
}
@media (min-width: 880px) {
  .cards {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 20px;
  }
}

/* ---------- cards ---------- */
.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 12px;
  transition: border-color 0.2s ease;
}
.card.is-right { border-color: var(--good); }
.card.is-wrong { border-color: var(--bad); }

.card-h {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px;
  margin: 2px 2px 8px;
}
.card-h .label {
  font-size: 17px;
  font-weight: 700;
}
.card-h .state {
  font-size: 13px;
  color: var(--sub);
}
.card.is-right .state { color: var(--good); font-weight: 600; }
.card.is-wrong .state { color: var(--bad); font-weight: 600; }

video {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 10px;
  background: #000;
}

.choices {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
  margin-top: 12px;
}
@media (min-width: 880px) {
  .choices { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}

.choice {
  min-height: 48px;
  padding: 8px 8px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--btn);
  color: var(--fg);
  font: inherit;
  font-size: 15px;
  line-height: 1.3;
  text-align: center;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}
.choice:hover:not(:disabled) { background: var(--btn-hover); }
.choice:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 2px;
}
.choice:disabled { cursor: default; }
.choice.out {
  opacity: 0.35;
  text-decoration: line-through;
}
.choice.right {
  background: var(--good-bg);
  border-color: var(--good);
  color: var(--good);
  font-weight: 700;
}
.choice.wrong {
  background: var(--bad-bg);
  border-color: var(--bad);
  color: var(--bad);
  font-weight: 700;
}
.choice.answer {
  border-color: var(--good);
  border-style: dashed;
  color: var(--good);
  font-weight: 700;
}

/* ---------- reveal ---------- */
.reveal {
  margin-top: 12px;
  padding: 12px;
  border-radius: 10px;
  background: var(--btn);
}
.reveal.ok { box-shadow: inset 3px 0 0 var(--good); }
.reveal.ng { box-shadow: inset 3px 0 0 var(--bad); }
.verdict {
  margin: 0 0 4px;
  font-size: 17px;
  font-weight: 700;
  transform-origin: left center;
}
.reveal.ok .verdict { color: var(--good); }
.reveal.ng .verdict { color: var(--bad); }
.truth {
  margin: 0 0 8px;
  font-size: 15px;
}
.truth strong { color: var(--fg); }
.facts {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 4px 12px;
  margin: 0;
  font-size: 14px;
}
.facts dt { color: var(--sub); white-space: nowrap; }
.facts dd { margin: 0; }

.verdict.pop { animation: pop 0.45s ease-out; }
.verdict.shake { animation: shake 0.45s ease-in-out; }

.badge {
  display: inline-block;
  margin: 0 0 8px;
  padding: 3px 10px;
  border-radius: 999px;
  background: var(--accent);
  color: var(--accent-fg);
  font-size: 13px;
  font-weight: 700;
}
.extra {
  margin: 10px 0 0;
  padding-top: 8px;
  border-top: 1px dashed var(--line);
  color: var(--sub);
  font-size: 13px;
}

/* ---------- finish + about ---------- */
.finish {
  margin: 24px 0 0;
  padding: 16px;
  border-radius: var(--radius);
  background: var(--card);
  border: 1px solid var(--accent);
  font-size: 16px;
}
.finish strong { color: var(--accent); }

.about {
  margin-top: 36px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
  color: var(--sub);
  font-size: 14px;
}
.about h2 {
  margin: 0 0 8px;
  font-size: 16px;
  color: var(--fg);
}
.about ul {
  margin: 0;
  padding-left: 1.2em;
}
.about li { margin: 6px 0; }

.loading,
.error {
  padding: 24px 0;
  color: var(--sub);
  text-align: center;
}
.error { color: var(--bad); }

/* ---------- intro overlay ---------- */
.intro {
  position: fixed;
  inset: 0;
  z-index: 100;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  padding: 16px;
  background: var(--bg);
  transition: opacity 0.35s ease;
}
.intro.out {
  opacity: 0;
  pointer-events: none;
}
.intro p {
  margin: 0;
  font-size: 17px;
  font-weight: 600;
  text-align: center;
}
.intro .track {
  position: relative;
  width: 180px;
  height: 4px;
  border-radius: 4px;
  background: var(--line);
  overflow: hidden;
}
.intro .track i {
  position: absolute;
  top: 0;
  left: -40%;
  width: 40%;
  height: 100%;
  border-radius: 4px;
  background: var(--accent);
  animation: slide 1.1s ease-in-out infinite;
}

/* ---------- speed chart ---------- */
.speed {
  margin-top: 36px;
  padding: 18px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}
.speed h2 {
  margin: 0 0 2px;
  font-size: 20px;
}
.speed-unit {
  margin: 0 0 12px;
  color: var(--sub);
  font-size: 13px;
}
.speed-verdict {
  margin: 0 0 16px;
  padding: 10px 12px;
  border-left: 3px solid var(--accent);
  border-radius: 8px;
  background: var(--btn);
  font-size: 15px;
}
.bars {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 14px;
}
.bar-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  grid-template-areas:
    "name val"
    "track track";
  gap: 6px 10px;
  align-items: center;
}
.bar-name { grid-area: name; min-width: 0; }
.bar-name .n { font-weight: 600; }
.bar-name .caveat {
  display: block;
  color: var(--sub);
  font-size: 12px;
  line-height: 1.4;
}
.bar-val {
  grid-area: val;
  font-weight: 600;
  white-space: nowrap;
  font-variant-numeric: tabular-nums;
}
.bar-track {
  grid-area: track;
  position: relative;
  height: 18px;
  border-radius: 6px;
  background-color: var(--btn);
  background-image: linear-gradient(to right, var(--line) 1px, transparent 1px);
  background-size: 25% 100%;
  overflow: hidden;
}
.bar-fill {
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  border-radius: 6px;
  background: var(--accent);
}
.bar-fill.cut::after {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  right: 0;
  width: 18px;
  background: repeating-linear-gradient(-45deg, var(--card) 0 3px, transparent 3px 6px);
}
.scale-note {
  margin: 14px 0 0;
  color: var(--sub);
  font-size: 13px;
}
.speed-notes {
  margin: 10px 0 0;
  padding-left: 1.2em;
  color: var(--sub);
  font-size: 13px;
}
.speed-notes li { margin: 4px 0; }

@media (min-width: 720px) {
  .bar-row {
    grid-template-columns: minmax(0, 220px) minmax(0, 1fr) auto;
    grid-template-areas: "name track val";
  }
}

/* ---------- motion ---------- */
@keyframes pop {
  0% { transform: scale(0.9); opacity: 0; }
  60% { transform: scale(1.04); opacity: 1; }
  100% { transform: scale(1); }
}
@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20% { transform: translateX(-6px); }
  40% { transform: translateX(6px); }
  60% { transform: translateX(-4px); }
  80% { transform: translateX(4px); }
}
@keyframes slide {
  to { left: 100%; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation: none !important;
    transition: none !important;
  }
}