/* Mandarin Tutor section — matches wjamm.com, sized for little fingers on an iPad */
:root {
  --bg: #faf8f4;
  --ink: #2b2620;
  --ink-soft: #6b6257;
  --accent: #3d6b4f;
  --rule: #e5dfd5;
  --card: #ffffff;
  --done-bg: #e3f1e7;
  --done-ink: #24543a;
  --learn-bg: #fbefd9;
  --learn-ink: #7a4d07;
  --learn-line: #e2b25c;
  --red: #b5432f;
  --zh: "PingFang SC", "Hiragino Sans GB", "Heiti SC", "Noto Sans SC", "Microsoft YaHei", sans-serif;
  color-scheme: light dark;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #191713;
    --ink: #ece7de;
    --ink-soft: #a89e90;
    --accent: #8fbf9f;
    --rule: #37322a;
    --card: #211e19;
    --done-bg: #1f3a2a;
    --done-ink: #b9e0c5;
    --learn-bg: #3d2d12;
    --learn-ink: #f3d39a;
    --learn-line: #a87a2c;
    --red: #e58a74;
  }
}
* { margin: 0; padding: 0; box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  background: var(--bg);
  color: var(--ink);
  font: 17px/1.55 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, var(--zh), sans-serif;
  -webkit-font-smoothing: antialiased;
  -webkit-tap-highlight-color: transparent;
}
.wrap { max-width: 52rem; margin: 0 auto; padding: 2rem 16px 4rem; }
.site-nav { font-size: 0.9rem; margin-bottom: 1.75rem; }
.site-nav a { color: var(--ink-soft); text-decoration: none; }
.site-nav a:hover { color: var(--accent); }
h1, h2 { line-height: 1.2; font-weight: 600; }
h1 { font-size: 2.1rem; margin-bottom: 0.35rem; }
h1 .zh, h2 .zh { font-family: var(--zh); }
h1 .en, h2 .en { color: var(--ink-soft); font-weight: 400; font-size: 0.6em; margin-left: 0.4rem; }
h2 { font-size: 1.5rem; margin: 2.5rem 0 1rem; }
.kicker {
  color: var(--accent);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: 0.5rem;
}
.sub { color: var(--ink-soft); margin-bottom: 1.5rem; }
a { color: var(--accent); }
button { font: inherit; color: inherit; cursor: pointer; border: none; background: none; }
button:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }
.icon { width: 1.4em; height: 1.4em; display: inline-block; vertical-align: middle; flex: none; }
footer.site {
  margin-top: 3.5rem; padding-top: 1.25rem; border-top: 1px solid var(--rule);
  color: var(--ink-soft); font-size: 0.85rem; text-align: center;
}
footer.site a { color: var(--ink-soft); text-decoration: none; }

/* ---- section index ---- */
.week-list { list-style: none; }
.week-list li { margin-bottom: 0.85rem; }
.week-list a {
  display: block; text-decoration: none; color: var(--ink);
  background: var(--card); border: 1px solid var(--rule); border-radius: 14px;
  padding: 1rem 1.25rem;
}
.week-list a:hover { border-color: var(--accent); }
.week-list .dates { color: var(--accent); font-size: 0.85rem; font-weight: 600; }
.week-list .what { display: block; font-size: 1.15rem; font-weight: 600; margin-top: 0.15rem; }

/* ---- checklist ---- */
.tasks { display: grid; gap: 12px; }
.task {
  display: flex; align-items: center; gap: 14px;
  background: var(--card); border: 1px solid var(--rule); border-radius: 16px;
  padding: 14px 16px; min-height: 76px;
}
.task.done { border-color: var(--accent); }
.task .check {
  width: 48px; height: 48px; border-radius: 50%; flex: none;
  border: 3px solid var(--rule); display: flex; align-items: center; justify-content: center;
  color: transparent;
}
.task.done .check { background: var(--accent); border-color: var(--accent); color: var(--bg); }
.task .body { flex: 1; min-width: 0; }
.task .title { font-size: 1.2rem; font-weight: 600; }
.task .title .zh { font-family: var(--zh); margin-right: 0.35rem; }
.task .meta { color: var(--ink-soft); font-size: 0.9rem; }
.task .go {
  flex: none; min-width: 56px; height: 56px; border-radius: 14px; padding: 0 14px;
  background: var(--done-bg); color: var(--done-ink); font-weight: 600;
  display: flex; align-items: center; justify-content: center; gap: 6px;
}
.days { display: inline-flex; gap: 5px; margin-left: 0.4rem; vertical-align: middle; }
.days i { width: 12px; height: 12px; border-radius: 50%; border: 2px solid var(--rule); display: inline-block; }
.days i.on { background: var(--accent); border-color: var(--accent); }
.steps { margin: 0.6rem 0 0 1.2rem; font-size: 1rem; }
.steps li { margin-bottom: 0.3rem; }
.task details summary { color: var(--accent); font-weight: 600; cursor: pointer; min-height: 32px; display: flex; align-items: center; }
.more-links { margin-top: 1rem; color: var(--ink-soft); font-size: 0.95rem; }
.more-links a { display: inline-block; margin: 0.25rem 0.75rem 0 0; }

/* ---- character grid ---- */
.grid-bar { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; margin-bottom: 14px; }
.chip {
  min-height: 48px; padding: 0 18px; border-radius: 999px; border: 2px solid var(--rule);
  background: var(--card); font-weight: 600; display: inline-flex; align-items: center; gap: 8px;
}
.chip .zh { font-family: var(--zh); }
.chip[aria-pressed="true"] { border-color: var(--accent); color: var(--accent); }
.chip .n { color: var(--ink-soft); font-weight: 400; font-size: 0.9rem; }
.grid-bar .spacer { flex: 1; }
.char-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(76px, 1fr)); gap: 10px; }
.tile {
  position: relative; aspect-ratio: 1; border-radius: 14px;
  background: var(--card); border: 2px solid var(--rule);
  font-family: var(--zh); font-size: 2.3rem; line-height: 1;
  display: flex; align-items: center; justify-content: center;
}
.tile.learning { background: var(--learn-bg); border-color: var(--learn-line); color: var(--learn-ink); }
.tile.done { background: var(--done-bg); border-color: var(--accent); color: var(--done-ink); }
.tile .badge { position: absolute; right: 5px; bottom: 5px; width: 18px; height: 18px; opacity: 0.85; }
.legend { display: flex; flex-wrap: wrap; gap: 6px 16px; color: var(--ink-soft); font-size: 0.85rem; margin-top: 12px; }
.legend span { display: inline-flex; align-items: center; gap: 6px; }
.legend .sw { width: 16px; height: 16px; border-radius: 5px; border: 2px solid var(--rule); background: var(--card); }
.legend .sw.learning { background: var(--learn-bg); border-color: var(--learn-line); }
.legend .sw.done { background: var(--done-bg); border-color: var(--accent); }
.empty { color: var(--ink-soft); padding: 1.5rem 0; text-align: center; }

/* ---- big card overlay ---- */
.overlay {
  position: fixed; inset: 0; z-index: 10; background: var(--bg);
  display: flex; flex-direction: column; align-items: center;
  padding: max(12px, env(safe-area-inset-top)) 16px max(16px, env(safe-area-inset-bottom));
}
.overlay[hidden] { display: none; }
.overlay { overflow-y: auto; }
.ov-top { width: 100%; max-width: 40rem; display: flex; align-items: center; justify-content: space-between; min-height: 56px; }
.round {
  width: 56px; height: 56px; border-radius: 50%; border: 2px solid var(--rule); background: var(--card);
  display: inline-flex; align-items: center; justify-content: center;
}
.count { color: var(--ink-soft); font-weight: 600; font-size: 1.05rem; }
.stage { flex: 1; width: 100%; max-width: 40rem; display: flex; align-items: center; justify-content: center; perspective: 1400px; min-height: 0; padding: 10px 0; }
.card {
  position: relative; width: 100%; max-width: 34rem; height: 100%; max-height: 34rem; min-height: 15rem;
  transform-style: preserve-3d; transition: transform 0.45s ease;
}
.card.flipped { transform: rotateY(180deg); }
.face {
  position: absolute; inset: 0; border-radius: 24px; background: var(--card); border: 2px solid var(--rule);
  backface-visibility: hidden; -webkit-backface-visibility: hidden;
  display: flex; flex-direction: column; align-items: center; justify-content: center; padding: 20px; text-align: center;
}
.card.is-done .face { border-color: var(--accent); }
.card.is-learning .face { border-color: var(--learn-line); }
.face.front .big { font-family: var(--zh); font-size: min(11rem, 30vh); line-height: 1; }
.face.back { transform: rotateY(180deg); gap: 6px; }
.face.back .mid { font-family: var(--zh); font-size: 4rem; line-height: 1; }
.face.back .py { font-size: 3rem; font-weight: 600; color: var(--accent); }
.face.back .en { font-size: 1.6rem; }
.face.back .built { color: var(--ink-soft); font-size: 1.2rem; max-width: 26rem; }
.face.back .rad { color: var(--ink-soft); font-size: 0.9rem; font-family: var(--zh); }
.flip-hint { position: absolute; bottom: 12px; right: 16px; color: var(--ink-soft); width: 26px; height: 26px; opacity: 0.6; }
.status { min-height: 4.2rem; width: 100%; max-width: 30rem; display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 8px; text-align: center; font-size: 1.15rem; font-weight: 600; }
.status .zh { font-family: var(--zh); font-size: 1.35rem; }
.status.good { color: var(--done-ink); }
.status.try { color: var(--learn-ink); }
.status.err { color: var(--red); }
.status .row { display: flex; gap: 10px; flex-wrap: wrap; justify-content: center; }
.pill {
  min-height: 52px; padding: 0 18px; border-radius: 999px; border: 2px solid var(--rule); background: var(--card);
  display: inline-flex; align-items: center; gap: 8px; font-weight: 600; font-size: 1rem;
}
.pill .zh { font-family: var(--zh); font-size: 1.15rem; }
.pill.yes { border-color: var(--accent); color: var(--accent); }
.controls { display: flex; align-items: center; justify-content: center; gap: 18px; padding-top: 6px; }
.mic {
  width: 96px; height: 96px; border-radius: 50%; background: var(--accent); color: var(--bg);
  display: inline-flex; align-items: center; justify-content: center;
}
.mic .icon { width: 44px; height: 44px; }
.mic.listening { animation: pulse 1s ease-in-out infinite; }
@keyframes pulse { 0%, 100% { box-shadow: 0 0 0 0 rgba(61, 107, 79, 0.45); } 50% { box-shadow: 0 0 0 18px rgba(61, 107, 79, 0); } }
.controls .round { width: 64px; height: 64px; }
.controls .round .icon { width: 30px; height: 30px; }
.burst { position: absolute; left: 50%; top: 50%; pointer-events: none; }
.burst i { position: absolute; width: 12px; height: 12px; border-radius: 50%; animation: fly 0.8s ease-out forwards; }
@keyframes fly { from { transform: translate(0, 0) scale(1); opacity: 1; } to { transform: translate(var(--x), var(--y)) scale(0.4); opacity: 0; } }

/* ---- facts drill ---- */
.drill { background: var(--card); border: 1px solid var(--rule); border-radius: 18px; padding: 18px 16px; }
.drill .pick { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 12px; }
.drill .pick .chip { min-width: 56px; justify-content: center; font-size: 1.15rem; }
.drill .start { display: flex; justify-content: center; margin-top: 10px; }
.big-btn {
  min-height: 64px; padding: 0 34px; border-radius: 999px; background: var(--accent); color: var(--bg);
  font-size: 1.3rem; font-weight: 700; display: inline-flex; align-items: center; gap: 10px;
}
.drill .best { text-align: center; color: var(--ink-soft); margin-top: 10px; }
.play { display: flex; flex-direction: column; align-items: center; gap: 12px; }
.timer { width: 100%; height: 12px; border-radius: 6px; background: var(--rule); overflow: hidden; }
.timer i { display: block; height: 100%; background: var(--accent); width: 100%; transition: width 0.25s linear; }
.problem { font-size: 3.4rem; font-weight: 700; font-variant-numeric: tabular-nums; letter-spacing: 0.02em; }
.answer {
  min-width: 7rem; min-height: 4.2rem; border-radius: 14px; border: 3px solid var(--rule);
  font-size: 2.8rem; font-weight: 700; text-align: center; font-variant-numeric: tabular-nums;
  display: flex; align-items: center; justify-content: center; padding: 0 12px;
}
.answer.right { border-color: var(--accent); color: var(--accent); }
.answer.wrong { border-color: var(--red); animation: shake 0.3s; }
@keyframes shake { 25% { transform: translateX(-8px); } 75% { transform: translateX(8px); } }
.pad { display: grid; grid-template-columns: repeat(3, 84px); gap: 10px; }
.pad button {
  height: 72px; border-radius: 16px; background: var(--bg); border: 2px solid var(--rule);
  font-size: 1.9rem; font-weight: 600; display: flex; align-items: center; justify-content: center;
}
.pad button:active { background: var(--done-bg); }
.score { font-size: 1.2rem; font-weight: 600; }
.result { text-align: center; display: flex; flex-direction: column; align-items: center; gap: 10px; }
.result .num { font-size: 4rem; font-weight: 800; color: var(--accent); line-height: 1; }
.notice {
  margin-top: 12px; padding: 12px 14px; border-radius: 12px; background: var(--learn-bg); color: var(--learn-ink); font-size: 0.95rem;
}
.notice[hidden] { display: none; }
.parent { margin-top: 2.5rem; color: var(--ink-soft); font-size: 0.85rem; }
.parent button { color: var(--ink-soft); text-decoration: underline; min-height: 44px; }
@media (max-width: 480px) {
  .controls { gap: 10px; }
  .controls .round { width: 52px; height: 52px; }
  .mic { width: 84px; height: 84px; }
  .pad { grid-template-columns: repeat(3, 72px); }
  .problem { font-size: 2.8rem; }
  .char-grid { grid-template-columns: repeat(auto-fill, minmax(64px, 1fr)); }
}
@media (max-height: 600px) {
  .stage { flex: 0 0 auto; min-height: 13rem; }
  .card { min-height: 12rem; }
  .face.front .big { font-size: 7rem; }
  .face.back .mid { font-size: 2.4rem; }
  .face.back .py { font-size: 2rem; }
  .face.back .en { font-size: 1.15rem; }
  .face.back .built { font-size: 0.95rem; }
}
@media (prefers-reduced-motion: reduce) {
  .card { transition: none; }
  .mic.listening, .burst i { animation: none; }
}