:root {
  --ink: #18202b;
  --muted: #667386;
  --paper: #f7f4ef;
  --panel: #ffffff;
  --line: #d9dfd9;
  --green: #1f6d58;
  --green-soft: #e3f3ec;
  --blue: #315f96;
  --blue-soft: #e8f0fb;
  --coral: #b85545;
  --coral-soft: #fae8e4;
  --gold: #946b26;
  --gold-soft: #fff2d5;
  --shadow: 0 18px 45px rgba(32, 38, 48, 0.12);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.58;
}

button,
input,
textarea {
  font: inherit;
}

.hero {
  position: relative;
  min-height: 58vh;
  display: grid;
  align-items: end;
  overflow: hidden;
  background: #23352f;
}

.hero-image,
.hero-overlay {
  position: absolute;
  inset: 0;
}

.hero-image {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.hero-overlay {
  background:
    linear-gradient(90deg, rgba(20, 25, 30, 0.78), rgba(20, 25, 30, 0.36) 48%, rgba(20, 25, 30, 0.12)),
    linear-gradient(0deg, rgba(247, 244, 239, 0.96), rgba(247, 244, 239, 0) 38%);
}

.hero-content {
  position: relative;
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto;
  padding: 48px 0 82px;
  color: #fff;
}

.eyebrow,
.section-kicker,
.dock-label {
  margin: 0 0 8px;
  color: var(--green);
  font-size: 13px;
  font-weight: 760;
  letter-spacing: 0;
  text-transform: uppercase;
}

.hero .eyebrow {
  color: #d9f4e9;
}

.home-link {
  display: inline-flex;
  align-items: center;
  min-height: 34px;
  margin-bottom: 16px;
  padding: 6px 10px;
  border: 1px solid rgba(255, 255, 255, 0.42);
  border-radius: 7px;
  color: rgba(255, 255, 255, 0.92);
  background: rgba(255, 255, 255, 0.12);
  font-size: 14px;
  font-weight: 760;
  text-decoration: none;
}

.home-link:hover {
  background: rgba(255, 255, 255, 0.2);
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1 {
  max-width: 740px;
  margin-bottom: 14px;
  font-size: clamp(44px, 8vw, 84px);
  line-height: 0.95;
  letter-spacing: 0;
}

.hero-copy {
  max-width: 620px;
  margin: 0;
  color: rgba(255, 255, 255, 0.92);
  font-size: 20px;
}

.shell {
  width: min(1180px, calc(100% - 28px));
  margin: -38px auto 96px;
  display: grid;
  grid-template-columns: 220px minmax(0, 1fr);
  gap: 22px;
  align-items: start;
  position: relative;
}

.sidebar {
  position: sticky;
  top: 18px;
  z-index: 2;
  display: grid;
  gap: 4px;
  padding: 14px;
  background: rgba(255, 255, 255, 0.88);
  border: 1px solid var(--line);
  border-radius: 8px;
  backdrop-filter: blur(12px);
  box-shadow: 0 8px 26px rgba(32, 38, 48, 0.07);
}

.sidebar a {
  display: block;
  padding: 9px 10px;
  border-radius: 6px;
  color: var(--muted);
  text-decoration: none;
  font-size: 14px;
  font-weight: 650;
}

.sidebar a:hover {
  color: var(--ink);
  background: var(--green-soft);
}

.lesson {
  display: grid;
  gap: 20px;
}

.section {
  padding: 28px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 10px 30px rgba(32, 38, 48, 0.06);
}

.section h2 {
  margin-bottom: 10px;
  font-size: clamp(26px, 4vw, 42px);
  line-height: 1.1;
  letter-spacing: 0;
}

.section h3 {
  margin-bottom: 8px;
  font-size: 20px;
  line-height: 1.25;
}

.section-note {
  max-width: 720px;
  color: var(--muted);
}

.intro-grid {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(320px, 1.1fr);
  gap: 24px;
}

.kit-list {
  display: grid;
  gap: 12px;
}

.kit-list > div {
  display: grid;
  grid-template-columns: 44px minmax(0, 1fr);
  gap: 0 12px;
  align-items: start;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
}

.kit-number {
  grid-row: span 2;
  display: grid;
  place-items: center;
  width: 38px;
  aspect-ratio: 1;
  border-radius: 50%;
  color: var(--green);
  background: var(--green-soft);
  font-weight: 800;
}

.kit-list p {
  margin: 2px 0 0;
  color: var(--muted);
  font-size: 14px;
}

.brief-layout {
  display: grid;
  grid-template-columns: minmax(280px, 0.9fr) minmax(360px, 1.1fr);
  gap: 28px;
  align-items: start;
}

.brief-copy p {
  max-width: 700px;
  color: var(--muted);
}

.system-rule {
  display: grid;
  gap: 6px;
  margin-top: 18px;
  padding: 16px 18px;
  border-left: 4px solid var(--green);
  border-radius: 0 8px 8px 0;
  color: #163427;
  background: var(--green-soft);
}

.system-rule strong,
.system-rule span {
  display: block;
}

.system-map {
  padding: 18px;
  border: 1px solid #cfd8ce;
  border-radius: 8px;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.74), rgba(255, 255, 255, 0.96)),
    linear-gradient(135deg, var(--blue-soft), var(--gold-soft));
}

.system-map-header {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 16px;
  color: var(--green);
  font-size: 12px;
  font-weight: 800;
  text-transform: uppercase;
}

.system-flow {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.system-node {
  min-height: 124px;
  padding: 14px;
  border: 1px solid rgba(89, 104, 90, 0.24);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.78);
}

.system-node span {
  display: grid;
  place-items: center;
  width: 28px;
  aspect-ratio: 1;
  margin-bottom: 10px;
  border-radius: 50%;
  color: #fff;
  background: var(--blue);
  font-size: 13px;
  font-weight: 820;
}

.system-node strong {
  display: block;
  margin-bottom: 5px;
  line-height: 1.2;
}

.system-node p {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.38;
}

.brief-check {
  margin-top: 12px;
  padding: 14px 16px;
  border-radius: 8px;
  color: #293346;
  background: rgba(255, 255, 255, 0.72);
}

.brief-check h3 {
  margin-bottom: 6px;
  font-size: 16px;
}

.brief-check ul {
  margin: 0;
  padding-left: 20px;
  color: var(--muted);
}

.brief-check li {
  margin: 4px 0;
}

.arrival-layout {
  display: grid;
  grid-template-columns: minmax(320px, 0.95fr) minmax(280px, 1fr);
  gap: 20px;
  align-items: start;
}

.arrival-card {
  padding: 18px;
  color: #1f2b26;
  background: #fcfbf6;
  border: 1px solid #cfd8ce;
  border-radius: 8px;
}

.arrival-card-header {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 18px;
  color: var(--green);
  font-size: 12px;
  font-weight: 800;
}

.arrival-card dl {
  margin: 0;
  display: grid;
  gap: 8px;
}

.arrival-card dt {
  color: var(--muted);
  font-size: 12px;
  font-weight: 720;
}

.arrival-card dd {
  margin: 0 0 8px;
  font-size: 18px;
  font-weight: 760;
}

.arrival-map {
  margin-top: 16px;
  min-height: 92px;
  display: grid;
  grid-template-columns: auto minmax(80px, 1fr) auto;
  gap: 14px;
  align-items: center;
  padding: 16px;
  border-radius: 8px;
  background: linear-gradient(135deg, #e8f0fb, #fff2d5);
  color: #415064;
  font-size: 13px;
  font-weight: 740;
}

.arrival-map i {
  display: block;
  height: 3px;
  background: repeating-linear-gradient(90deg, var(--blue), var(--blue) 8px, transparent 8px, transparent 16px);
}

.action-panel {
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--blue-soft);
}

.phrase-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}

.phrase-grid.compact {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.phrase-card {
  display: grid;
  gap: 12px;
  min-height: 220px;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
}

.phrase-card.is-active {
  border-color: rgba(31, 109, 88, 0.8);
  box-shadow: 0 12px 34px rgba(31, 109, 88, 0.2);
}

.phrase-meta {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  align-items: center;
  color: var(--muted);
  font-size: 12px;
  font-weight: 760;
  text-transform: uppercase;
}

.chunk-line {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  color: #11191f;
  font-family: "PingFang SC", "Microsoft YaHei", ui-sans-serif, system-ui, sans-serif;
  font-size: clamp(26px, 4vw, 36px);
  font-weight: 780;
  line-height: 1.25;
}

.chunk-unit {
  appearance: none;
  border: 0;
  cursor: pointer;
  display: inline-block;
  padding: 1px 5px 3px;
  border-radius: 6px;
  color: inherit;
  background: transparent;
  font: inherit;
  transition: background-color 120ms ease, color 120ms ease, transform 120ms ease, box-shadow 120ms ease;
}

.chunk-unit:hover {
  color: #0f3f31;
  background: #eef8f3;
}

.chunk-unit:focus-visible {
  outline: 3px solid rgba(49, 95, 150, 0.28);
  outline-offset: 2px;
}

.chunk-unit.is-spoken {
  color: #1f5e4c;
  background: #e1f4eb;
}

.chunk-unit.is-highlighted {
  color: #071711;
  background: #9fe0c0;
  box-shadow: 0 0 0 3px rgba(31, 109, 88, 0.14);
  transform: translateY(-2px);
}

.pinyin {
  margin: 0;
  color: var(--blue);
  font-size: 15px;
  font-weight: 720;
}

.pron-helper {
  border-top: 1px solid #eef1ed;
  padding-top: 10px;
}

.pron-helper summary {
  cursor: pointer;
  color: var(--green);
  font-size: 13px;
  font-weight: 760;
}

.pron-helper p {
  margin: 8px 0;
  color: var(--muted);
  font-size: 13px;
}

.sounds-like {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.sounds-like span {
  display: inline-grid;
  gap: 1px;
  padding: 7px 9px;
  border-radius: 7px;
  background: #f4f8f5;
}

.sounds-like strong {
  color: var(--ink);
  font-size: 13px;
}

.sounds-like em {
  color: var(--blue);
  font-size: 13px;
  font-style: normal;
  font-weight: 720;
}

.meaning,
.action {
  margin: 0;
  color: var(--muted);
  font-size: 15px;
}

.action {
  padding: 10px 12px;
  border-radius: 8px;
  color: var(--gold);
  background: var(--gold-soft);
  font-weight: 680;
}

.phrase-controls {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: auto;
}

.phrase-controls button {
  min-width: 98px;
  min-height: 40px;
  border: 1px solid transparent;
  border-radius: 7px;
  cursor: pointer;
  color: white;
  background: var(--green);
  font-weight: 760;
}

.phrase-controls button.secondary {
  color: var(--green);
  background: #fff;
  border-color: rgba(31, 109, 88, 0.35);
}

.phrase-controls button:hover {
  filter: brightness(0.96);
}

.scene-list {
  display: grid;
  gap: 14px;
}

.scene-block {
  display: grid;
  grid-template-columns: minmax(240px, 0.8fr) minmax(0, 1.2fr);
  gap: 18px;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
}

.scene-block:nth-child(2n) {
  background: #fbfaf7;
}

.scene-block p {
  color: var(--muted);
}

.keyword-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.keyword-row span {
  padding: 5px 9px;
  border-radius: 999px;
  color: var(--blue);
  background: var(--blue-soft);
  font-size: 13px;
  font-weight: 720;
}

.scene-phrases {
  display: grid;
  gap: 10px;
}

.scene-phrases .phrase-card {
  min-height: 0;
}

.practice ol {
  margin: 0;
  padding-left: 24px;
}

.practice li {
  margin: 10px 0;
}

.lesson-cta {
  color: #fff;
  background:
    linear-gradient(135deg, rgba(31, 109, 88, 0.94), rgba(49, 95, 150, 0.92)),
    #1f6d58;
}

.lesson-cta .section-kicker,
.lesson-cta p {
  color: rgba(255, 255, 255, 0.86);
}

.lesson-cta h2 {
  color: #fff;
}

.lesson-cta-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 18px;
}

.lesson-cta-actions a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 11px 16px;
  border: 1px solid rgba(255, 255, 255, 0.45);
  border-radius: 7px;
  color: #fff;
  font-weight: 780;
  text-decoration: none;
}

.lesson-cta-actions a:first-child {
  color: var(--green);
  background: #fff;
  border-color: #fff;
}

.audio-dock {
  position: fixed;
  left: 50%;
  bottom: 16px;
  z-index: 10;
  width: min(680px, calc(100% - 28px));
  transform: translateX(-50%);
  display: grid;
  grid-template-columns: minmax(180px, 1fr) minmax(120px, 220px);
  gap: 18px;
  align-items: center;
  padding: 14px 16px;
  border: 1px solid rgba(31, 109, 88, 0.18);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.94);
  box-shadow: var(--shadow);
  backdrop-filter: blur(14px);
}

.audio-dock strong {
  display: block;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.dock-label {
  margin-bottom: 2px;
}

.dock-progress {
  height: 8px;
  overflow: hidden;
  border-radius: 999px;
  background: #e6ebe5;
}

.dock-progress span {
  display: block;
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--green), var(--blue));
  transition: width 120ms linear;
}

@media (max-width: 900px) {
  .shell {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: static;
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .intro-grid,
  .brief-layout,
  .arrival-layout,
  .scene-block,
  .phrase-grid,
  .phrase-grid.compact {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 620px) {
  .hero {
    min-height: 64vh;
  }

  .hero-content {
    padding-bottom: 68px;
  }

  .section {
    padding: 20px;
  }

  .system-flow {
    grid-template-columns: 1fr;
  }

  .system-map-header {
    display: grid;
    gap: 2px;
  }

  .sidebar {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .audio-dock {
    grid-template-columns: 1fr;
  }
}