:root {
  --paper: #f4efe4;
  --paper-deep: #e7dcc8;
  --ink: #1d1914;
  --muted: #6f655a;
  --card: #fffaf3;
  --line: rgba(40, 30, 18, 0.12);
  --coral: #e15b3a;
  --teal: #0f766c;
  --violet: #5344a6;
  --gold: #b67912;
  --blend: #1d6a9a;
  --green: #1d7a45;
  --shadow: 0 16px 40px rgba(70, 46, 18, 0.08);
  --radius: 22px;
  font-family: "Noto Sans SC", "PingFang SC", "Nunito", "Avenir Next", sans-serif;
  color: var(--ink);
}

* { box-sizing: border-box; }

html, body { margin: 0; min-height: 100%; }

body {
  background:
    radial-gradient(circle at 12% -10%, #ffe7c2 0%, transparent 42%),
    radial-gradient(circle at 100% 0%, #d9f3ee 0%, transparent 36%),
    var(--paper);
  color: var(--ink);
}

button, input { font: inherit; color: inherit; }

button { cursor: pointer; }

button:focus-visible {
  outline: 3px solid #1d6a9a;
  outline-offset: 3px;
}

#app { min-height: 100vh; }

.topbar {
  position: sticky;
  top: 0;
  z-index: 5;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  padding: 14px 22px;
  background: rgba(244, 239, 228, 0.9);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}

.brand, .text-btn, .back {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  background: transparent;
  border: 0;
  padding: 0;
  text-align: left;
}

.brand strong { display: block; font-size: 1.15rem; letter-spacing: 0.02em; }
.brand small, .muted, .status { color: var(--muted); }

.logo {
  width: 46px;
  height: 46px;
  border-radius: 14px;
  display: grid;
  place-items: center;
  background: var(--ink);
  color: #fff8ea;
  font-family: Nunito, "Avenir Next", sans-serif;
  font-weight: 900;
  font-size: 1.15rem;
}

.topbar nav { display: flex; gap: 8px; flex-wrap: wrap; }

.topbar nav button, .shelf-btn, .choice, .mini, .demo-tile, .path-card, .rule-card, .speed-btn {
  border: 1.5px solid var(--line);
  background: var(--card);
  border-radius: 999px;
}

.topbar nav button { padding: 8px 14px; font-weight: 700; }
.topbar nav button.on { background: var(--ink); color: #fffaf3; border-color: var(--ink); }

main { max-width: 1080px; margin: 0 auto; padding: 28px 20px 64px; }

.hero { display: grid; grid-template-columns: 1.3fr 0.9fr; gap: 28px; align-items: center; }
.kicker { letter-spacing: 0.16em; text-transform: uppercase; font-size: 0.78rem; color: var(--coral); font-weight: 800; margin: 0 0 8px; }
h1 { font-size: clamp(2.2rem, 5vw, 3.6rem); line-height: 1.15; margin: 0 0 12px; font-weight: 900; }
.lead { font-size: 1.12rem; line-height: 1.7; margin: 0 0 18px; }
.hero-actions, .pager, .controls, .listens, .action-grid { display: flex; flex-wrap: wrap; gap: 12px; }

.btn {
  border: 0;
  border-radius: 16px;
  padding: 13px 18px;
  font-weight: 800;
  background: var(--ink);
  color: #fffaf3;
}
.btn.light { background: transparent; color: var(--ink); border: 1.5px solid var(--line); }
.btn-blend { background: var(--green); color: white; border: 0; border-radius: 16px; padding: 13px 18px; font-weight: 800; }
.btn-sound { background: var(--teal); color: white; border: 0; border-radius: 16px; padding: 13px 18px; font-weight: 800; }
.btn:disabled { opacity: 0.4; cursor: default; }

.demo {
  background: var(--card);
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: var(--shadow);
  border: 1px solid var(--line);
}
.demo p { margin: 0 0 12px; font-weight: 800; }
.demo-row { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; }
.demo-tile {
  border-radius: 18px;
  min-height: 84px;
  font-family: Nunito, "Avenir Next", sans-serif;
  font-size: 2rem;
  font-weight: 900;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2px;
}
.demo-tile small { font-family: "Noto Sans SC", sans-serif; font-size: 0.85rem; font-weight: 700; color: var(--muted); }

.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; margin: 28px 0; }
.step, .rule-card, .path-card, .stage, .lesson, .panel {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}
.step { padding: 16px 18px; }
.step b { display: block; margin-bottom: 6px; }
.step span { color: var(--muted); line-height: 1.6; }

.path { display: flex; flex-direction: column; gap: 12px; }
.path-card {
  width: 100%;
  text-align: left;
  border-radius: 20px;
  padding: 16px 18px;
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: 14px;
  align-items: center;
}
.path-card:hover { transform: translateY(-1px); }
.num {
  width: 48px; height: 48px; border-radius: 16px;
  display: grid; place-items: center;
  background: var(--paper-deep); font-weight: 900;
}
.path-card strong { display: block; font-size: 1.08rem; }
.path-card small { display: block; color: var(--muted); line-height: 1.45; }
.star small { color: var(--muted); font-size: 0.78rem; }
.star { font-weight: 900; color: var(--gold); }
.star.off { color: #c8beae; }

.page-head { margin-bottom: 18px; }
.back { color: var(--muted); font-weight: 700; margin-bottom: 10px; }
.chips { display: flex; flex-wrap: wrap; gap: 8px; margin: 14px 0 18px; }
.mini {
  border-radius: 16px;
  min-width: 72px;
  padding: 8px 10px;
  font-family: Nunito, "Avenir Next", sans-serif;
  font-weight: 900;
  font-size: 1.25rem;
  display: flex;
  flex-direction: column;
  align-items: center;
}
.mini small { font-family: "Noto Sans SC", sans-serif; font-size: 0.75rem; color: var(--muted); font-weight: 700; }

.action-grid { display: grid; grid-template-columns: repeat(4, 1fr); margin: 8px 0 12px; }
.action-grid button {
  border-radius: 18px;
  border: 1px solid var(--line);
  background: var(--card);
  padding: 18px 12px;
  font-weight: 800;
  box-shadow: var(--shadow);
}
.action-grid button span { display: block; color: var(--muted); font-weight: 600; font-size: 0.86rem; margin-top: 4px; }

.lesson { padding: 28px 22px 22px; text-align: center; }
.giant {
  width: min(100%, 280px);
  min-height: 150px;
  margin: 8px auto 8px;
  border-radius: 28px;
  display: grid;
  place-items: center;
  font-family: Nunito, "Avenir Next", sans-serif;
  font-weight: 900;
  font-size: 5rem;
  letter-spacing: -0.04em;
  border: 4px solid currentColor;
  background: white;
}
.giant.wide { font-size: 3.4rem; }
.ipa-lg { font-size: 1.6rem; margin: 8px 0; font-weight: 800; }
.hint { max-width: 640px; margin: 0 auto 16px; line-height: 1.7; color: #3d342b; }
.keyword {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 8px 14px;
  border-radius: 999px;
  background: var(--paper);
  margin-bottom: 16px;
  font-weight: 800;
}
.dots { display: flex; justify-content: center; gap: 6px; margin: 8px 0 16px; }
.dots i { width: 8px; height: 8px; border-radius: 99px; background: #ddd3c4; display: block; }
.dots i.on { background: var(--ink); width: 22px; }

.kind-vowel { color: var(--coral); }
.kind-consonant { color: var(--teal); }
.kind-team { color: var(--violet); }
.kind-magic { color: var(--gold); }
.kind-blend { color: var(--blend); }

.shelf {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding: 4px 2px 12px;
  margin-bottom: 8px;
}
.shelf-btn { padding: 8px 14px; font-weight: 800; white-space: nowrap; border-radius: 999px; }
.shelf-btn.active { background: var(--ink); color: #fffaf3; border-color: var(--ink); }

.stage { padding: 28px 18px 22px; text-align: center; }
.track {
  display: flex;
  justify-content: center;
  align-items: flex-start;
  gap: 18px;
  min-height: 150px;
  transition: gap 0.45s cubic-bezier(0.34, 1.56, 0.64, 1);
}
.slot { display: flex; flex-direction: column; align-items: center; }
.card {
  min-width: 92px;
  height: 100px;
  padding: 0 12px;
  border-radius: 22px;
  border: 4px solid currentColor;
  background: white;
  font-family: Nunito, "Avenir Next", sans-serif;
  font-size: 3rem;
  font-weight: 900;
  letter-spacing: -0.04em;
  box-shadow: 0 10px 0 rgba(40, 30, 18, 0.05);
}
.card.wide { font-size: 2.1rem; }
.card:hover { transform: translateY(-3px); }
.card.active {
  transform: translateY(-8px) scale(1.08);
  background: #fff;
  box-shadow: 0 14px 0 rgba(40, 30, 18, 0.1);
}
.ipa { margin-top: 8px; color: var(--muted); font-weight: 800; background: var(--paper); border-radius: 999px; padding: 2px 8px; }

.stage.merged .track { gap: 0; }
.stage.merged .card {
  border-radius: 0;
  color: white;
  background: var(--green);
  border-color: #166538;
  box-shadow: none;
}
.stage.merged .slot:first-child .card { border-top-left-radius: 22px; border-bottom-left-radius: 22px; }
.stage.merged .slot:last-child .card { border-top-right-radius: 22px; border-bottom-right-radius: 22px; }
.stage.merged .ipa { opacity: 0; }

.result {
  min-height: 74px;
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 12px;
  opacity: 0;
  transform: scale(0.8);
  transition: 0.35s cubic-bezier(0.34, 1.56, 0.64, 1);
}
.result.show { opacity: 1; transform: none; }
.result b { display: block; font-size: 2rem; color: var(--green); letter-spacing: 0.04em; }
.result small { color: var(--muted); font-weight: 700; }
.res-emoji { font-size: 3rem; animation: bob 0.7s ease-in-out infinite alternate; }
.sentence { font-size: 1.7rem; line-height: 2; }
.sentence button {
  border: 0;
  background: transparent;
  font-weight: 900;
  border-bottom: 3px solid var(--line);
  margin: 0 3px;
  padding: 0 2px;
}
.sentence button.on { color: var(--coral); border-color: var(--coral); }
.formula { min-height: 28px; color: var(--muted); font-weight: 800; opacity: 0; }
.formula.show { opacity: 1; }
.controls { justify-content: center; margin-top: 8px; }

@keyframes bob { from { transform: translateY(0); } to { transform: translateY(-6px); } }

.quiz-card, .reflex-card, .rule-card, .panel { padding: 22px; }
.choices { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 16px; }
.choice {
  border-radius: 18px;
  min-height: 84px;
  padding: 12px;
  font-weight: 800;
  font-size: 1.35rem;
}
.choice small { display: block; color: var(--muted); font-size: 0.9rem; margin-top: 4px; }
.choice.good { background: #e7f6ec; border-color: var(--green); }
.choice.bad { background: #fde8e3; border-color: var(--coral); }
.feedback { margin-top: 14px; font-weight: 800; }
.progress-label { color: var(--muted); font-weight: 700; }

.reflex-face {
  min-height: 220px;
  display: grid;
  place-items: center;
  font-family: Nunito, "Avenir Next", sans-serif;
  font-weight: 900;
  font-size: 7rem;
  letter-spacing: -0.05em;
  background: white;
  border-radius: 28px;
  border: 4px solid var(--ink);
  margin: 12px 0;
}
.reflex-face small {
  display: block;
  font-family: "Noto Sans SC", sans-serif;
  font-size: 1.1rem;
  letter-spacing: 0;
  color: var(--muted);
  font-weight: 800;
}
.speed-row { display: flex; gap: 8px; margin: 12px 0; }
.speed-btn { padding: 8px 12px; font-weight: 800; }
.speed-btn.on { background: var(--ink); color: white; }

.rule-list { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.rule-card { text-align: left; padding: 18px; }
.rule-card b { display: block; margin-bottom: 6px; font-size: 1.08rem; }
.rule-card span { color: var(--muted); line-height: 1.55; }

.pairs { display: flex; flex-wrap: wrap; gap: 10px; justify-content: center; margin: 12px 0; }
.pair { display: flex; gap: 6px; align-items: center; }
.pair i { color: var(--muted); font-style: normal; font-weight: 900; }

.footer {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 20px 28px;
  color: var(--muted);
  font-size: 0.86rem;
  line-height: 1.6;
}
.footer button { background: none; border: 0; color: var(--muted); text-decoration: underline; padding: 0; }

@media (max-width: 800px) {
  .hero, .steps, .action-grid, .rule-list, .choices { grid-template-columns: 1fr 1fr; }
  .hero { grid-template-columns: 1fr; }
  .topbar { flex-direction: column; align-items: stretch; }
  .reflex-face { font-size: 5rem; min-height: 170px; }
  .card { min-width: 64px; height: 78px; font-size: 2.1rem; padding: 0 8px; }
  .card.wide { font-size: 1.45rem; }
  .track { gap: 6px; }
}

@media (max-width: 560px) {
  .steps, .action-grid, .rule-list { grid-template-columns: 1fr; }
  .demo-row { grid-template-columns: repeat(3, 1fr); }
}

@media (prefers-reduced-motion: reduce) {
  .res-emoji { animation: none; }
  .track, .result, .card { transition: none; }
}