:root {
  --bg-start: #faf7f0;
  --bg-end: #efe6d7;
  --panel: rgba(255, 252, 246, 0.9);
  --panel-strong: #fffaf0;
  --line: rgba(68, 51, 33, 0.14);
  --text: #1f1a14;
  --muted: #67594b;
  --accent: #0d7c66;
  --accent-soft: rgba(13, 124, 102, 0.12);
  --danger: #b24a2f;
  --shadow: 0 18px 48px rgba(69, 48, 22, 0.12);
  --radius-xl: 28px;
  --radius-lg: 18px;
  --radius-md: 12px;
  --font-ui: "Avenir Next", "Segoe UI", "Helvetica Neue", Arial, sans-serif;
  --font-display: "Avenir Next", "Segoe UI", "Helvetica Neue", Arial, sans-serif;
}

body[data-theme="dark"] {
  --bg-start: #161c1d;
  --bg-end: #0f1314;
  --panel: rgba(22, 28, 29, 0.88);
  --panel-strong: #1b2224;
  --line: rgba(202, 220, 214, 0.12);
  --text: #edf3ef;
  --muted: #b5c2bb;
  --accent: #61c3a8;
  --accent-soft: rgba(97, 195, 168, 0.14);
  --danger: #ff8d73;
  --shadow: 0 18px 48px rgba(0, 0, 0, 0.32);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--text);
  font-family: var(--font-ui);
  font-size: 17px;
  line-height: 1.6;
  background:
    radial-gradient(circle at top left, rgba(242, 181, 68, 0.16), transparent 30%),
    radial-gradient(circle at top right, rgba(13, 124, 102, 0.14), transparent 24%),
    linear-gradient(180deg, var(--bg-start) 0%, var(--bg-end) 100%);
}

.page-shell {
  width: min(1200px, calc(100% - 32px));
  margin: 0 auto;
  padding: 22px 0 40px;
}

.hero {
  display: grid;
  margin-bottom: 12px;
}

.hero-controls {
  display: flex;
  justify-content: flex-end;
  flex-wrap: wrap;
  gap: 8px;
}

.card {
  border: 1px solid var(--line);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow);
  backdrop-filter: blur(14px);
}

.eyebrow,
.section-kicker {
  margin: 0 0 8px;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.12em;
  font-size: 0.73rem;
  font-weight: 700;
}

h1,
h2,
h3 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 700;
}

h2 {
  font-size: clamp(1.5rem, 2vw, 2rem);
  line-height: 1.2;
}

h3 {
  font-size: 1.06rem;
  margin-bottom: 10px;
}

.lesson-intro,
.word-panel p,
.exercise-block p,
#reviewIntro {
  color: var(--muted);
  line-height: 1.7;
}

select,
.choice-button,
.secondary-button {
  font: inherit;
}

.grid {
  display: block;
}

.card {
  background: var(--panel);
  padding: 18px;
}

.page-section {
  display: grid;
  gap: 16px;
}

.page-section-main {
  grid-template-columns: minmax(0, 1.45fr) minmax(280px, 0.9fr);
}

.page-section-exercises {
  grid-template-columns: minmax(0, 1.1fr) minmax(280px, 0.9fr);
}

.page-section-game {
  grid-template-columns: 1fr;
}

.lesson-card,
.exercises-card,
.game-card {
  grid-column: 1 / 2;
}

.word-card,
.word-day-card,
.review-card {
  grid-column: 2 / 3;
}

.lesson-button {
  margin-top: 16px;
}

.lesson-switch {
  margin-bottom: 16px;
}

.card-head {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  align-items: start;
  margin-bottom: 16px;
}

.lesson-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.pill {
  padding: 8px 12px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.85rem;
  font-weight: 700;
}

.primary-button {
  border: 0;
  border-radius: 999px;
  background: var(--accent);
  color: white;
  padding: 12px 16px;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
}

.primary-button:hover {
  transform: translateY(-1px);
}

.sentence-list {
  margin: 18px 0 0;
  display: grid;
  gap: 14px;
}

.sentence-item {
  line-height: 1.85;
}

.dialogue-line,
.story-line {
  padding: 10px 12px;
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.18);
}

.dialogue-line {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 10px;
}

.speaker {
  color: var(--accent);
  font-weight: 700;
}

.story-paragraph {
  margin: 0;
  line-height: 1.95;
  color: var(--text);
}

.tap-word {
  border: 0;
  background: rgba(13, 124, 102, 0.08);
  color: inherit;
  padding: 1px 4px;
  border-radius: 6px;
  cursor: pointer;
}

.tap-word:hover,
.tap-word:focus-visible {
  outline: none;
  color: var(--accent);
  background: rgba(13, 124, 102, 0.16);
}

.word-details {
  display: grid;
  gap: 12px;
}

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

.tab-button {
  border: 1px solid var(--line);
  background: transparent;
  color: var(--muted);
  border-radius: 999px;
  padding: 8px 12px;
  font: inherit;
  cursor: pointer;
}

.tab-button.active {
  background: var(--accent-soft);
  color: var(--accent);
  border-color: transparent;
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.word-term {
  font-size: 1.28rem;
  color: var(--text);
  font-weight: 700;
}

.word-definition {
  font-size: 1.02rem;
}

.word-example {
  font-style: italic;
  line-height: 1.7;
}

.word-day-sentence {
  margin: 12px 0 0;
  color: var(--text);
  line-height: 1.6;
}

.hidden {
  display: none;
}

.secondary-button,
.choice-button {
  border: 1px solid var(--line);
  background: var(--panel-strong);
  border-radius: 14px;
  padding: 10px 12px;
  color: var(--text);
  cursor: pointer;
  transition: transform 160ms ease, border-color 160ms ease, background 160ms ease;
}

.toolbar-button {
  min-width: 58px;
  padding: 8px 10px;
  border-radius: 999px;
}

.theme-toggle {
  border: 1px solid var(--line);
  background: var(--panel-strong);
  border-radius: 999px;
  padding: 4px;
  width: 54px;
  height: 36px;
  cursor: pointer;
}

.theme-toggle-track {
  display: flex;
  align-items: center;
  width: 100%;
  height: 100%;
}

.theme-toggle-thumb {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  transform: translateX(0);
  transition: transform 160ms ease;
  font-size: 0.9rem;
}

.theme-toggle.dark .theme-toggle-thumb {
  transform: translateX(18px);
}

.secondary-button:hover,
.choice-button:hover {
  transform: translateY(-1px);
  border-color: rgba(13, 124, 102, 0.5);
}

.exercise-block + .exercise-block {
  margin-top: 26px;
  padding-top: 22px;
  border-top: 1px solid var(--line);
}

.choice-row,
.choice-grid {
  display: grid;
  gap: 10px;
  margin-top: 14px;
}

.choice-row {
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
}

.choice-grid {
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
}

.choice-button.correct {
  border-color: rgba(13, 124, 102, 0.7);
  background: rgba(13, 124, 102, 0.13);
  color: var(--accent);
}

.choice-button.wrong {
  border-color: rgba(178, 74, 47, 0.55);
  background: rgba(178, 74, 47, 0.1);
  color: var(--danger);
}

.feedback {
  min-height: 24px;
  margin-top: 10px;
  font-weight: 600;
  line-height: 1.5;
}

.game-board {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
  margin-top: 16px;
}

.game-column {
  display: grid;
  gap: 12px;
}

.game-list {
  display: grid;
  gap: 10px;
}

.game-option.active {
  border-color: rgba(13, 124, 102, 0.7);
  background: rgba(13, 124, 102, 0.13);
  color: var(--accent);
}

.saved-words {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 16px;
}

.saved-word {
  padding: 10px 12px;
  border-radius: 999px;
  background: rgba(31, 26, 20, 0.06);
  color: var(--text);
}

.mastered-panel {
  margin-top: 18px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
}

.mastered-word {
  background: rgba(13, 124, 102, 0.14);
  color: var(--accent);
}

@media (max-width: 920px) {
  .page-section-main,
  .page-section-exercises,
  .page-section-game {
    grid-template-columns: 1fr;
  }

  .lesson-card,
  .exercises-card,
  .review-card,
  .word-card,
  .word-day-card {
    grid-column: auto;
  }

  .hero-controls {
    justify-content: space-between;
  }
}

@media (max-width: 640px) {
  .page-shell {
    width: min(100%, calc(100% - 20px));
    padding: 14px 0 28px;
  }

  .hero {
    position: sticky;
    top: 0;
    z-index: 5;
    padding-top: 2px;
    margin-bottom: 10px;
  }

  .hero-controls {
    justify-content: flex-start;
    gap: 6px;
    padding-bottom: 6px;
    backdrop-filter: blur(10px);
  }

  .toolbar-button,
  .theme-toggle {
    min-width: 0;
  }

  .card {
    padding: 14px;
    border-radius: 20px;
  }

  .card-head {
    flex-direction: column;
    gap: 10px;
    margin-bottom: 12px;
  }

  h2 {
    font-size: 1.28rem;
  }

  .lesson-intro,
  .story-paragraph,
  .word-day-sentence,
  .dialogue-line,
  .story-line {
    font-size: 1rem;
  }

  .dialogue-line {
    grid-template-columns: 1fr;
    gap: 4px;
  }

  .sentence-list {
    gap: 10px;
  }

  .tab-row {
    gap: 6px;
  }

  .tab-button,
  .secondary-button,
  .choice-button {
    padding: 9px 11px;
  }

  .choice-row,
  .choice-grid {
    grid-template-columns: 1fr;
  }

  .game-board {
    grid-template-columns: 1fr;
  }

  .saved-words {
    gap: 8px;
  }
}