:root {
  color-scheme: light dark;
  --page: #f3f6f4;
  --surface: #fbfcfb;
  --surface-strong: #ffffff;
  --surface-muted: #e8eeeb;
  --ink: #18231f;
  --muted: #5c6964;
  --line: #cdd8d2;
  --accent: #176b52;
  --accent-strong: #0f5741;
  --accent-soft: #d9eee6;
  --accent-ink: #0d4937;
  --danger: #a44343;
  --shadow: 0 18px 48px rgba(40, 69, 57, 0.11);
  --card-radius: 18px;
  --control-radius: 12px;
  --max-width: 1180px;
  font-family: "SF Pro Text", "Segoe UI", "PingFang SC", "Hiragino Sans GB", system-ui, sans-serif;
}

:root[data-theme="dark"] {
  --page: #111714;
  --surface: #161f1b;
  --surface-strong: #1c2823;
  --surface-muted: #24312b;
  --ink: #edf4f0;
  --muted: #a8b8b0;
  --line: #34453d;
  --accent: #72c4a7;
  --accent-strong: #91d8be;
  --accent-soft: #1f4638;
  --accent-ink: #d8f5ea;
  --danger: #f09a9a;
  --shadow: 0 18px 48px rgba(0, 0, 0, 0.22);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-width: 320px;
  background: var(--page);
  color: var(--ink);
  line-height: 1.6;
  text-rendering: optimizeLegibility;
}

button,
input,
select {
  font: inherit;
}

button,
a,
input,
select {
  -webkit-tap-highlight-color: transparent;
}

button,
a {
  touch-action: manipulation;
}

button {
  cursor: pointer;
}

button:focus-visible,
a:focus-visible,
input:focus-visible,
select:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--accent) 55%, transparent);
  outline-offset: 3px;
}

.skip-link {
  position: fixed;
  left: 16px;
  top: 12px;
  z-index: 20;
  padding: 9px 14px;
  border-radius: var(--control-radius);
  background: var(--ink);
  color: var(--page);
  transform: translateY(-160%);
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  min-height: 70px;
  align-items: center;
  justify-content: space-between;
  width: min(calc(100% - 40px), var(--max-width));
  margin: 0 auto;
  background: color-mix(in srgb, var(--page) 88%, transparent);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid color-mix(in srgb, var(--line) 75%, transparent);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  color: var(--ink);
  text-decoration: none;
}

.brand-mark {
  display: grid;
  width: 38px;
  height: 38px;
  place-items: center;
  border-radius: var(--control-radius);
  background: var(--accent);
  color: var(--page);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.04em;
}

.brand strong,
.brand small {
  display: block;
}

.brand strong {
  font-size: 15px;
  line-height: 1.2;
}

.brand small {
  margin-top: 2px;
  color: var(--muted);
  font-size: 10px;
  letter-spacing: 0.08em;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 18px;
}

.header-progress {
  color: var(--muted);
  font-size: 13px;
  font-variant-numeric: tabular-nums;
}

.text-button {
  border: 0;
  padding: 4px 0;
  background: transparent;
  color: var(--accent);
  font-size: 13px;
  font-weight: 700;
}

.text-button:hover {
  color: var(--accent-strong);
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(360px, 0.95fr);
  gap: clamp(42px, 8vw, 112px);
  align-items: center;
  width: min(calc(100% - 40px), var(--max-width));
  min-height: min(680px, calc(100dvh - 70px));
  margin: 0 auto;
  padding: 72px 0 68px;
}

.eyebrow {
  margin: 0 0 16px;
  color: var(--accent);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.13em;
}

.hero h1 {
  max-width: 660px;
  margin: 0;
  font-size: clamp(42px, 6vw, 74px);
  line-height: 1.03;
  letter-spacing: -0.055em;
}

.hero-subtitle {
  max-width: 540px;
  margin: 24px 0 30px;
  color: var(--muted);
  font-size: clamp(17px, 2vw, 20px);
}

.primary-link,
.primary-button,
.secondary-button {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  border-radius: var(--control-radius);
  padding: 10px 17px;
  text-decoration: none;
  font-weight: 760;
  transition: background-color 160ms ease, color 160ms ease, border-color 160ms ease, transform 160ms ease;
}

.primary-link,
.primary-button {
  border: 1px solid var(--accent);
  background: var(--accent);
  color: var(--page);
}

.primary-link:hover,
.primary-button:hover {
  border-color: var(--accent-strong);
  background: var(--accent-strong);
}

.secondary-button {
  border: 1px solid var(--line);
  background: var(--surface-strong);
  color: var(--ink);
}

.secondary-button:hover {
  border-color: var(--accent);
  color: var(--accent-strong);
}

.primary-link:active,
.primary-button:active,
.secondary-button:active,
.category-tab:active,
.master-button:active {
  transform: translateY(1px);
}

.hero-practice {
  position: relative;
  overflow: hidden;
  min-height: 370px;
  padding: clamp(28px, 5vw, 48px);
  border: 1px solid var(--line);
  border-radius: var(--card-radius);
  background:
    linear-gradient(145deg, color-mix(in srgb, var(--accent-soft) 62%, transparent), transparent 54%),
    var(--surface-strong);
  box-shadow: var(--shadow);
}

.hero-practice::after {
  content: "listen";
  position: absolute;
  right: -12px;
  bottom: -40px;
  color: color-mix(in srgb, var(--accent) 10%, transparent);
  font-size: 92px;
  font-weight: 900;
  letter-spacing: -0.08em;
  pointer-events: none;
}

.hero-practice-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  color: var(--muted);
  font-size: 12px;
}

.hero-learning-content {
  position: relative;
  z-index: 1;
  display: flex;
  min-height: 250px;
  flex-direction: column;
  justify-content: center;
  padding: 34px 0 68px;
}

.hero-learning-content .sentence-english {
  margin: 0 0 14px;
  font-size: clamp(25px, 3vw, 36px);
}

.hero-learning-content .keyword-only-panel,
.hero-learning-content .listening-prompt {
  margin: 0;
}

.hero-learning-content .source-link {
  margin-top: 16px;
}

.voice-note {
  text-align: right;
}

.hero-english {
  position: relative;
  z-index: 1;
  max-width: 460px;
  margin: 70px 0 14px;
  font-size: clamp(27px, 3vw, 38px);
  font-weight: 720;
  line-height: 1.22;
  letter-spacing: -0.025em;
}

.hero-chinese {
  position: relative;
  z-index: 1;
  margin: 0;
  color: var(--muted);
  font-size: 15px;
}

.hero-practice-actions {
  position: absolute;
  z-index: 2;
  left: clamp(28px, 5vw, 48px);
  bottom: 38px;
  display: flex;
  gap: 10px;
}

.hero-practice-actions .secondary-button {
  flex: 1.35;
}

.hero-practice-actions button {
  padding-right: 12px;
  padding-left: 12px;
  font-size: 13px;
  white-space: nowrap;
}

.method-strip {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  width: min(calc(100% - 40px), var(--max-width));
  margin: 0 auto;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.method-strip p {
  display: grid;
  grid-template-columns: 54px 1fr;
  gap: 14px;
  align-items: baseline;
  margin: 0;
  padding: 24px 26px;
}

.method-strip p + p {
  border-left: 1px solid var(--line);
}

.method-strip strong {
  color: var(--accent);
  font-size: 22px;
}

.method-strip span {
  color: var(--muted);
  font-size: 14px;
}

.learning-section {
  width: min(calc(100% - 40px), var(--max-width));
  margin: 0 auto;
  padding: 100px 0 88px;
}

.section-heading {
  max-width: 700px;
  margin-bottom: 32px;
}

.section-heading h2 {
  margin: 0;
  font-size: clamp(34px, 5vw, 56px);
  line-height: 1.08;
  letter-spacing: -0.04em;
}

.section-heading p {
  margin: 14px 0 0;
  color: var(--muted);
  font-size: 16px;
}

.controls {
  display: grid;
  grid-template-columns: minmax(220px, 1.35fr) minmax(220px, 1fr) minmax(240px, 1fr) auto;
  gap: 12px;
  align-items: end;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--card-radius);
  background: var(--surface);
}

.control-block {
  min-width: 0;
}

.control-block > label,
.control-label {
  display: block;
  margin-bottom: 7px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 700;
}

input[type="search"],
select {
  width: 100%;
  min-height: 44px;
  border: 1px solid var(--line);
  border-radius: var(--control-radius);
  background: var(--surface-strong);
  color: var(--ink);
  padding: 9px 12px;
}

input[type="search"]::placeholder {
  color: color-mix(in srgb, var(--muted) 82%, transparent);
}

.switch-row {
  display: flex !important;
  min-height: 44px;
  align-items: center;
  gap: 10px;
  margin: 0 !important;
  padding: 8px 12px;
  border: 1px solid var(--line);
  border-radius: var(--control-radius);
  background: var(--surface-strong);
  color: var(--ink) !important;
  font-size: 13px !important;
}

.switch-row input {
  width: 17px;
  height: 17px;
  margin: 0;
  accent-color: var(--accent);
}

.mode-note {
  min-height: 44px;
  margin: 0;
  padding: 8px 12px;
  border: 1px solid var(--line);
  border-radius: var(--control-radius);
  background: var(--surface-strong);
  color: var(--ink);
  font-size: 13px;
  line-height: 1.45;
}

.control-actions {
  display: flex;
  gap: 8px;
}

.control-actions .secondary-button {
  white-space: nowrap;
}

.category-tabs {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  margin: 22px 0 28px;
  padding: 2px 0 8px;
  scrollbar-width: thin;
}

.category-tab {
  flex: 0 0 auto;
  min-height: 38px;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 7px 14px;
  background: transparent;
  color: var(--muted);
  font-size: 13px;
  font-weight: 720;
  white-space: nowrap;
  transition: background-color 160ms ease, color 160ms ease, border-color 160ms ease, transform 160ms ease;
}

.category-tab:hover,
.category-tab[aria-current="true"] {
  border-color: var(--accent);
  background: var(--accent-soft);
  color: var(--accent-ink);
}

.list-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  margin-bottom: 16px;
}

.list-toolbar p {
  margin: 0;
  color: var(--muted);
  font-size: 13px;
}

.danger-text {
  color: var(--danger);
}

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

.sentence-card {
  display: flex;
  min-height: 322px;
  flex-direction: column;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: var(--card-radius);
  background: var(--surface-strong);
  transition: border-color 180ms ease, transform 180ms ease, box-shadow 180ms ease;
}

.sentence-card:hover {
  border-color: color-mix(in srgb, var(--accent) 58%, var(--line));
  transform: translateY(-2px);
  box-shadow: 0 12px 34px color-mix(in srgb, var(--accent) 9%, transparent);
}

.sentence-card.is-playing {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 16%, transparent);
}

.sentence-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.sentence-meta-left {
  display: flex;
  min-width: 0;
  flex-direction: column;
  gap: 3px;
}

.sentence-number {
  color: var(--muted);
  font-size: 12px;
  font-variant-numeric: tabular-nums;
  font-weight: 720;
}

.source-link {
  width: fit-content;
  color: var(--accent-strong);
  font-size: 12px;
  font-weight: 700;
  text-decoration: underline;
  text-decoration-color: color-mix(in srgb, var(--accent) 45%, transparent);
  text-underline-offset: 3px;
}

.source-link:hover {
  text-decoration-color: var(--accent);
}

.source-link-compact {
  color: var(--muted);
  font-size: 11px;
  font-weight: 620;
}

.master-button {
  min-height: 32px;
  border: 1px solid var(--line);
  border-radius: var(--control-radius);
  padding: 5px 10px;
  background: transparent;
  color: var(--muted);
  font-size: 12px;
  font-weight: 700;
  transition: background-color 160ms ease, color 160ms ease, border-color 160ms ease, transform 160ms ease;
}

.master-button:hover,
.master-button.is-mastered {
  border-color: var(--accent);
  background: var(--accent-soft);
  color: var(--accent-ink);
}

.sentence-english {
  display: grid;
  gap: 8px;
  margin: 20px 0 8px;
  font-size: clamp(21px, 2.6vw, 28px);
  font-weight: 690;
  line-height: 1.3;
  letter-spacing: -0.025em;
}

.sentence-view-switch {
  display: flex;
  width: fit-content;
  margin-bottom: 4px;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 3px;
  background: var(--surface-muted);
}

.sentence-view-button {
  min-height: 28px;
  border: 0;
  border-radius: 999px;
  padding: 4px 10px;
  background: transparent;
  color: var(--muted);
  font-size: 11px;
  font-weight: 760;
}

.sentence-view-button.is-active {
  background: var(--surface-strong);
  color: var(--accent-strong);
  box-shadow: 0 1px 4px color-mix(in srgb, var(--ink) 10%, transparent);
}

.sentence-original {
  display: grid;
  grid-template-columns: 1fr 22px;
  align-items: center;
  gap: 12px;
  width: 100%;
  border: 1px solid var(--line);
  border-radius: var(--control-radius);
  padding: 16px;
  background: var(--surface-muted);
  color: var(--ink);
  text-align: left;
  transition: border-color 160ms ease, background-color 160ms ease, transform 160ms ease;
}

.sentence-original:hover {
  border-color: var(--accent);
  background: var(--accent-soft);
  transform: translateY(-1px);
}

.sentence-chunk {
  display: grid;
  grid-template-columns: 28px 1fr 22px;
  align-items: center;
  gap: 10px;
  width: 100%;
  border: 1px solid var(--line);
  border-radius: var(--control-radius);
  padding: 10px 12px;
  background: var(--surface-muted);
  color: var(--ink);
  text-align: left;
  transition: border-color 160ms ease, background-color 160ms ease, transform 160ms ease;
}

.sentence-chunk:hover {
  border-color: var(--accent);
  background: var(--accent-soft);
  transform: translateY(-1px);
}

.sentence-chunk-number {
  display: grid;
  width: 26px;
  height: 26px;
  place-items: center;
  border-radius: 50%;
  background: var(--accent-soft);
  color: var(--accent-ink);
  font-size: 12px;
  font-weight: 800;
}

.sentence-chunk-text {
  min-width: 0;
}

.sentence-chunk-play {
  color: var(--accent-strong);
  font-size: 12px;
}

.sentence-english mark {
  border-radius: 4px;
  background: var(--accent-soft);
  color: var(--accent-ink);
  padding: 0 3px 1px;
}

.sentence-translation {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
}

.stage-content {
  display: flex;
  min-height: 208px;
  flex: 1;
  flex-direction: column;
  justify-content: center;
  padding: 18px 0;
}

.listening-prompt {
  display: flex;
  min-height: 132px;
  flex-direction: column;
  justify-content: center;
  border: 1px dashed var(--line);
  border-radius: var(--control-radius);
  padding: 20px;
  background: var(--surface-muted);
}

.audio-prompt {
  margin: 0;
  color: var(--ink);
  font-size: 23px;
  font-weight: 760;
  letter-spacing: -0.025em;
}

.audio-instruction {
  margin: 7px 0 0;
  color: var(--muted);
  font-size: 13px;
}

.blind-chunk-controls {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
  margin-top: 18px;
}

.chunk-audio-button {
  min-height: 38px;
  border: 1px solid var(--line);
  border-radius: var(--control-radius);
  padding: 7px 9px;
  background: var(--page);
  color: var(--accent-strong);
  font-size: 12px;
  font-weight: 760;
}

.chunk-audio-button:hover {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.keyword-only-panel {
  display: flex;
  min-height: 132px;
  flex-direction: column;
  align-items: flex-start;
  justify-content: center;
  gap: 9px;
  border: 1px solid var(--line);
  border-radius: var(--control-radius);
  padding: 20px;
  background: var(--accent-soft);
  color: var(--muted);
  font-size: 12px;
  font-weight: 700;
}

.keyword-button-large {
  border-bottom-width: 2px;
  color: var(--accent-ink);
  font-size: clamp(22px, 3vw, 29px);
  letter-spacing: -0.02em;
}

.stage-2 .keyword-only-panel {
  min-height: auto;
  margin-top: 18px;
  padding: 12px 14px;
}

.stage-2 .keyword-button-large {
  font-size: 18px;
}

.keyword-meaning {
  width: fit-content;
  margin: 14px 0 0;
  border-radius: var(--control-radius);
  padding: 8px 11px;
  background: var(--accent-soft);
  color: var(--accent-ink);
  font-size: 13px;
  font-weight: 720;
}

.source-proof {
  margin-top: 18px;
  padding-top: 14px;
  border-top: 1px solid var(--line);
}

.hidden-sentence {
  display: flex;
  min-height: 84px;
  align-items: center;
  margin: 18px 0 6px;
  border: 1px dashed var(--line);
  border-radius: var(--control-radius);
  padding: 14px;
  background: var(--surface-muted);
}

.reveal-button {
  border: 0;
  background: transparent;
  color: var(--accent-strong);
  font-weight: 760;
}

.keyword-row {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  margin: auto 0 18px;
  padding-top: 22px;
  color: var(--muted);
  font-size: 13px;
}

.keyword-button {
  border: 0;
  border-bottom: 1px solid var(--accent);
  padding: 0 0 1px;
  background: transparent;
  color: var(--accent-strong);
  font-weight: 760;
}

.card-actions {
  display: grid;
  grid-template-columns: 0.9fr 0.9fr 0.9fr 1.5fr;
  gap: 8px;
}

.card-actions button {
  min-height: 40px;
  padding: 8px 9px;
  font-size: 12px;
  white-space: nowrap;
}

.card-actions .help-button {
  white-space: normal;
}

.empty-state {
  padding: 72px 24px;
  border: 1px dashed var(--line);
  border-radius: var(--card-radius);
  background: var(--surface);
  text-align: center;
}

.empty-state h3 {
  margin: 0;
  font-size: 24px;
}

.empty-state p {
  margin: 8px 0 20px;
  color: var(--muted);
}

.pagination {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 18px;
  margin-top: 30px;
}

.pagination[hidden] {
  display: none;
}

#page-status {
  color: var(--muted);
  font-size: 13px;
  font-variant-numeric: tabular-nums;
}

.toast {
  position: fixed;
  z-index: 30;
  right: 20px;
  bottom: 20px;
  max-width: min(360px, calc(100% - 40px));
  border: 1px solid var(--line);
  border-radius: var(--control-radius);
  padding: 12px 16px;
  background: var(--ink);
  color: var(--page);
  box-shadow: var(--shadow);
  font-size: 13px;
}

footer {
  display: flex;
  justify-content: space-between;
  gap: 32px;
  width: min(calc(100% - 40px), var(--max-width));
  margin: 0 auto;
  padding: 30px 0 40px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 12px;
}

footer p {
  max-width: 520px;
  margin: 0;
}

@media (max-width: 980px) {
  .hero {
    grid-template-columns: 1fr;
    min-height: auto;
    padding: 72px 0;
  }

  .hero-copy {
    max-width: 720px;
  }

  .controls {
    grid-template-columns: 1fr 1fr;
  }

  .control-actions {
    justify-content: flex-end;
  }
}

@media (max-width: 720px) {
  .site-header,
  .hero,
  .method-strip,
  .learning-section,
  footer {
    width: min(calc(100% - 28px), var(--max-width));
  }

  .site-header {
    min-height: 64px;
  }

  .header-progress {
    display: none;
  }

  .hero {
    gap: 36px;
    padding: 58px 0 56px;
  }

  .hero h1 {
    font-size: clamp(40px, 13vw, 58px);
  }

  .hero-practice {
    min-height: 360px;
  }

  .hero-english {
    margin-top: 56px;
  }

  .method-strip {
    grid-template-columns: 1fr;
  }

  .method-strip p + p {
    border-top: 1px solid var(--line);
    border-left: 0;
  }

  .learning-section {
    padding: 74px 0 68px;
  }

  .controls {
    grid-template-columns: 1fr;
  }

  .control-actions {
    display: grid;
    grid-template-columns: 1fr 1fr;
  }

  .sentence-list {
    grid-template-columns: 1fr;
  }

  .sentence-card {
    min-height: 308px;
    padding: 20px;
  }

  .sentence-english {
    font-size: 24px;
  }

  .list-toolbar {
    align-items: flex-start;
  }

  footer {
    flex-direction: column;
    gap: 8px;
  }
}

@media (max-width: 430px) {
  .header-actions .text-button {
    font-size: 12px;
  }

  .hero-practice-actions {
    right: 24px;
    left: 24px;
  }

  .hero-practice-actions button {
    flex: 1;
  }

  .card-actions {
    grid-template-columns: 1fr 1fr;
  }

  .blind-chunk-controls {
    gap: 6px;
  }

  .sentence-chunk {
    grid-template-columns: 25px 1fr 18px;
    padding: 9px 10px;
  }

  .pagination {
    gap: 10px;
  }

  .pagination button {
    padding-right: 12px;
    padding-left: 12px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}