/* === Tokens === */
:root {
  --bg: #faf9f7;
  --bg-card: #ffffff;
  --bg-hover: #f3f1ee;
  --ink: #1a1824;
  --ink-2: #5c5873;
  --ink-3: #8a86a0;
  --border: #e5e2dc;
  --accent: #e85d2a;
  --accent-light: #fff3ee;
  --accent-dark: #c44a1c;
  --green: #16a34a;
  --green-bg: #f0fdf4;
  --blue: #2563eb;
  --blue-bg: #eff6ff;
  --gold: #d97706;
  --gold-bg: #fffbeb;
  --radius: 10px;
  --shadow: 0 1px 4px rgba(26,24,36,.07);
  --shadow-lg: 0 4px 16px rgba(26,24,36,.1);
  --font-zh: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --transition: 0.18s ease;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0e0d16;
    --bg-card: #1a1829;
    --bg-hover: #242236;
    --ink: #e8e6f0;
    --ink-2: #9e9ab3;
    --ink-3: #6e6a85;
    --border: #2a2740;
    --accent: #f4845f;
    --accent-light: #2a1a14;
    --accent-dark: #fb923c;
    --green: #4ade80;
    --green-bg: #0a2014;
    --blue: #60a5fa;
    --blue-bg: #0f1a2e;
    --gold: #fbbf24;
    --gold-bg: #2a2210;
    --shadow: 0 1px 4px rgba(0,0,0,.25);
    --shadow-lg: 0 4px 16px rgba(0,0,0,.35);
  }
}
:root[data-theme="dark"] {
  --bg: #0e0d16;
  --bg-card: #1a1829;
  --bg-hover: #242236;
  --ink: #e8e6f0;
  --ink-2: #9e9ab3;
  --ink-3: #6e6a85;
  --border: #2a2740;
  --accent: #f4845f;
  --accent-light: #2a1a14;
  --accent-dark: #fb923c;
  --green: #4ade80;
  --green-bg: #0a2014;
  --blue: #60a5fa;
  --blue-bg: #0f1a2e;
  --gold: #fbbf24;
  --gold-bg: #2a2210;
  --shadow: 0 1px 4px rgba(0,0,0,.25);
  --shadow-lg: 0 4px 16px rgba(0,0,0,.35);
}

/* === Reset === */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: var(--font); background: var(--bg); color: var(--ink); line-height: 1.6; -webkit-font-smoothing: antialiased; }
a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-dark); }
img { max-width: 100%; display: block; }
input, button { font-family: inherit; font-size: inherit; }

/* === Top bar === */
.top-bar { position: sticky; top: 0; z-index: 100; background: var(--bg-card); border-bottom: 1px solid var(--border); backdrop-filter: blur(12px); }
.top-bar-inner { max-width: 1100px; margin: 0 auto; padding: 0.5rem 1.25rem; display: flex; align-items: center; gap: 1rem; }
.logo { display: flex; align-items: center; gap: 0.5rem; text-decoration: none; flex-shrink: 0; }
.logo-img { width: 34px; height: 34px; border-radius: 8px; }
.logo-text { font-weight: 700; font-size: 1.15rem; color: var(--accent); letter-spacing: -0.02em; }
.search-box { position: relative; flex: 1; max-width: 400px; }
.search-box input {
  width: 100%; padding: 0.45rem 0.8rem; border: 1px solid var(--border); border-radius: 8px;
  background: var(--bg); color: var(--ink); font-size: 0.85rem; outline: none; transition: border var(--transition);
}
.search-box input:focus { border-color: var(--accent); }
.search-dropdown {
  position: absolute; top: calc(100% + 4px); left: 0; right: 0; background: var(--bg-card);
  border: 1px solid var(--border); border-radius: 8px; box-shadow: var(--shadow-lg); max-height: 360px; overflow-y: auto; z-index: 200;
}
.search-item { padding: 0.55rem 0.8rem; cursor: pointer; display: flex; align-items: baseline; gap: 0.5rem; border-bottom: 1px solid var(--border); }
.search-item:last-child { border-bottom: none; }
.search-item:hover { background: var(--bg-hover); }
.search-item .hz { font-family: var(--font-zh); font-size: 1.1rem; font-weight: 600; }
.search-item .py { color: var(--accent); font-size: 0.82rem; }
.search-item .vi { color: var(--ink-2); font-size: 0.82rem; margin-left: auto; }
.top-stats { font-size: 0.75rem; color: var(--ink-3); white-space: nowrap; flex-shrink: 0; }

/* === Main content === */
main { max-width: 1100px; margin: 0 auto; padding: 1.5rem 1.25rem 3rem; }

/* === Home: Hero === */
.hero { text-align: center; padding: 2rem 0 1.5rem; }
.hero-mascot { width: 120px; height: auto; margin: 0 auto 1rem; }
.hero h1 { font-size: 1.6rem; font-weight: 700; letter-spacing: -0.02em; }
.hero h1 .zh { font-family: var(--font-zh); }
.hero p { color: var(--ink-2); margin-top: 0.35rem; font-size: 0.95rem; }
.stats-bar { display: flex; justify-content: center; gap: 1.5rem; margin-top: 1rem; }
.stat { text-align: center; }
.stat-num { font-size: 1.4rem; font-weight: 700; color: var(--accent); font-variant-numeric: tabular-nums; }
.stat-label { font-size: 0.72rem; color: var(--ink-3); text-transform: uppercase; letter-spacing: 0.06em; }

/* === Level cards === */
.level-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 0.9rem; margin-top: 1.5rem; }
.level-card {
  background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 1.1rem 1.2rem; cursor: pointer; transition: all var(--transition); box-shadow: var(--shadow);
  display: flex; flex-direction: column; gap: 0.5rem;
}
.level-card:hover { border-color: var(--accent); box-shadow: var(--shadow-lg); transform: translateY(-2px); }
.level-card-head { display: flex; align-items: center; gap: 0.75rem; }
.level-badge {
  width: 44px; height: 44px; border-radius: 10px; display: flex; align-items: center; justify-content: center;
  font-family: var(--font-zh); font-weight: 700; font-size: 1.1rem; color: #fff; flex-shrink: 0;
}
.level-badge.l1 { background: #16a34a; }
.level-badge.l2 { background: #2563eb; }
.level-badge.l3 { background: #7c3aed; }
.level-badge.l4 { background: #db2777; }
.level-badge.l5 { background: #ea580c; }
.level-badge.l6 { background: #0891b2; }
.level-badge.l7 { background: #be123c; }
.level-card-title { font-weight: 700; font-size: 1.05rem; }
.level-card-title .est { font-weight: 400; font-size: 0.78rem; color: var(--ink-3); margin-left: 0.3rem; }
.level-card-desc { font-size: 0.85rem; color: var(--ink-2); }
.level-card-meta { display: flex; gap: 1rem; font-size: 0.78rem; color: var(--ink-3); margin-top: auto; }
.level-card-meta span { display: flex; align-items: center; gap: 0.25rem; }

/* === Level detail page === */
.breadcrumb { font-size: 0.82rem; color: var(--ink-3); margin-bottom: 1rem; }
.breadcrumb a { color: var(--ink-2); }
.breadcrumb a:hover { color: var(--accent); }
.level-header { display: flex; align-items: center; gap: 1rem; margin-bottom: 1.5rem; }
.level-header h1 { font-size: 1.35rem; font-weight: 700; }
.level-header .desc { color: var(--ink-2); font-size: 0.9rem; }

.tabs { display: flex; gap: 0; border-bottom: 2px solid var(--border); margin-bottom: 1.2rem; }
.tab {
  padding: 0.55rem 1.2rem; font-size: 0.88rem; font-weight: 600; color: var(--ink-3);
  cursor: pointer; border-bottom: 2px solid transparent; margin-bottom: -2px; transition: all var(--transition);
}
.tab:hover { color: var(--ink); }
.tab.active { color: var(--accent); border-bottom-color: var(--accent); }

/* === Units / Lessons === */
.unit-section { margin-bottom: 1.5rem; }
.unit-title { font-size: 0.88rem; font-weight: 700; color: var(--ink-2); margin-bottom: 0.6rem; padding: 0.3rem 0; border-bottom: 1px solid var(--border); }
.lesson-list { display: flex; flex-direction: column; gap: 0.35rem; }
.lesson-row {
  display: flex; align-items: center; gap: 0.75rem; padding: 0.6rem 0.8rem; border-radius: 8px;
  cursor: pointer; transition: background var(--transition); text-decoration: none; color: inherit;
}
.lesson-row:hover { background: var(--bg-hover); }
.lesson-num { width: 28px; height: 28px; border-radius: 50%; background: var(--accent-light); color: var(--accent); font-weight: 700; font-size: 0.78rem; display: flex; align-items: center; justify-content: center; flex-shrink: 0; }
.lesson-info { flex: 1; min-width: 0; }
.lesson-name { font-weight: 600; font-size: 0.9rem; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.lesson-name .zh { font-family: var(--font-zh); color: var(--ink-2); font-weight: 400; margin-left: 0.4rem; font-size: 0.85rem; }
.lesson-desc { font-size: 0.78rem; color: var(--ink-3); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.lesson-meta { font-size: 0.72rem; color: var(--ink-3); white-space: nowrap; flex-shrink: 0; text-align: right; display: flex; align-items: center; gap: 0.3rem; }
.lesson-chevron { font-size: 1rem; color: var(--ink-3); transition: color var(--transition); }
.lesson-row:hover .lesson-chevron { color: var(--accent); }

/* === Lesson Detail Page === */
.loading { text-align: center; padding: 3rem; color: var(--ink-3); font-size: 1rem; }
.ld-header { display: flex; align-items: flex-start; gap: 1rem; margin-bottom: 1.5rem; }
.ld-title { font-size: 1.3rem; font-weight: 700; letter-spacing: -0.02em; }
.ld-title .zh { font-family: var(--font-zh); color: var(--accent); font-weight: 600; margin-left: 0.4rem; }
.ld-desc { color: var(--ink-2); font-size: 0.9rem; margin-top: 0.2rem; }
.ld-tags { display: flex; gap: 0.5rem; flex-wrap: wrap; margin-top: 0.5rem; }
.ld-tag { font-size: 0.78rem; color: var(--ink-2); background: var(--bg); padding: 0.25rem 0.6rem; border-radius: 6px; border: 1px solid var(--border); }

.ld-section { margin-bottom: 2rem; }
.ld-section-title { font-size: 1.05rem; font-weight: 700; margin-bottom: 0.8rem; padding-bottom: 0.4rem; border-bottom: 2px solid var(--border); }

/* Dialogue */
.dialogue-box { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); padding: 1rem; margin-bottom: 0.8rem; box-shadow: var(--shadow); }
.dialogue-title { font-weight: 700; font-size: 0.95rem; margin-bottom: 0.2rem; }
.dialogue-scenario { font-size: 0.82rem; color: var(--ink-3); margin-bottom: 0.8rem; font-style: italic; }
.dialogue-turns { display: flex; flex-direction: column; gap: 0.6rem; }
.dialogue-turn { display: flex; gap: 0.6rem; align-items: flex-start; }
.turn-speaker { font-family: var(--font-zh); font-weight: 700; font-size: 0.82rem; color: var(--accent); min-width: 3rem; padding-top: 0.35rem; text-align: right; flex-shrink: 0; }
.turn-bubble { flex: 1; background: var(--bg); padding: 0.5rem 0.75rem; border-radius: 8px; border: 1px solid var(--border); }
.turn-hz { font-family: var(--font-zh); font-size: 1.05rem; font-weight: 500; line-height: 1.5; }
.turn-py { font-size: 0.78rem; color: var(--accent); margin-top: 0.1rem; }
.turn-vi { font-size: 0.82rem; color: var(--ink-2); margin-top: 0.15rem; }

/* Lesson grammar */
.ld-grammar-card { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); padding: 1rem; margin-bottom: 0.6rem; box-shadow: var(--shadow); }
.ld-grammar-pattern { font-family: var(--font-zh); font-size: 1.15rem; font-weight: 700; color: var(--accent); margin-bottom: 0.2rem; }
.ld-grammar-title { font-weight: 600; font-size: 0.95rem; margin-bottom: 0.5rem; }
.ld-grammar-explanation { font-size: 0.88rem; color: var(--ink-2); line-height: 1.65; }
.ld-grammar-explanation p { margin-bottom: 0.4rem; }
.ld-grammar-examples { margin-top: 0.6rem; display: flex; flex-direction: column; gap: 0.3rem; }

/* Lesson vocab grid */
.ld-vocab-grid { display: flex; flex-direction: column; gap: 0.3rem; }

/* Empty / back */
.ld-empty { text-align: center; padding: 3rem 1rem; color: var(--ink-3); }
.ld-empty-icon { font-size: 3rem; margin-bottom: 0.5rem; }
.ld-back-btn { display: inline-block; margin-top: 1rem; padding: 0.5rem 1.5rem; background: var(--accent); color: #fff; border-radius: 8px; font-weight: 600; font-size: 0.88rem; }
.ld-back-btn:hover { background: var(--accent-dark); color: #fff; }

/* Synthetic lesson notice */
.ld-notice { display: flex; gap: 0.7rem; align-items: flex-start; padding: 0.8rem 1rem; background: var(--gold-bg); border: 1px solid #fbbf2440; border-radius: var(--radius); margin-bottom: 1.2rem; }
.ld-notice-icon { font-size: 1.3rem; flex-shrink: 0; margin-top: 0.1rem; }
.ld-notice-text { font-size: 0.85rem; color: var(--ink-2); line-height: 1.5; }
.ld-notice-text strong { color: var(--ink); }

/* Fallback links for lessons without grammar/vocab */
.ld-fallback { text-align: center; padding: 1.5rem; background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); margin-top: 0.5rem; }
.ld-fallback-desc { font-size: 0.95rem; color: var(--ink-2); line-height: 1.6; margin-bottom: 1rem; }
.ld-fallback-links { display: flex; gap: 0.7rem; justify-content: center; flex-wrap: wrap; }
.ld-link-btn { display: inline-block; padding: 0.5rem 1.2rem; background: var(--accent-light); color: var(--accent); border-radius: 8px; font-weight: 600; font-size: 0.85rem; border: 1px solid var(--accent)30; }
.ld-link-btn:hover { background: var(--accent); color: #fff; }

/* Play button animation */
.play-btn.playing { animation: pulse 0.6s ease infinite alternate; }
@keyframes pulse { from { opacity: 1; } to { opacity: 0.5; } }

/* Vocab note */
.vocab-note { font-size: 0.8rem; color: var(--ink-3); margin-top: 0.2rem; }

/* === Vocab table === */
.vocab-controls { display: flex; gap: 0.6rem; align-items: center; margin-bottom: 1rem; flex-wrap: wrap; }
.vocab-search { padding: 0.4rem 0.7rem; border: 1px solid var(--border); border-radius: 6px; background: var(--bg); color: var(--ink); flex: 1; min-width: 200px; font-size: 0.85rem; }
.vocab-search:focus { outline: none; border-color: var(--accent); }
.vocab-count { font-size: 0.78rem; color: var(--ink-3); white-space: nowrap; }

.vocab-grid { display: flex; flex-direction: column; gap: 0.3rem; }
.vocab-card {
  background: var(--bg-card); border: 1px solid var(--border); border-radius: 8px;
  padding: 0.7rem 0.9rem; display: grid; grid-template-columns: auto 1fr auto; gap: 0.4rem 0.8rem; align-items: baseline;
  transition: border var(--transition); cursor: pointer;
}
.vocab-card:hover { border-color: var(--accent); }
.vocab-card.expanded { grid-template-columns: 1fr; border-color: var(--accent); }
.vocab-hz { font-family: var(--font-zh); font-size: 1.35rem; font-weight: 600; line-height: 1.3; }
.vocab-py { color: var(--accent); font-size: 0.88rem; }
.vocab-vi { color: var(--ink-2); font-size: 0.88rem; text-align: right; }
.vocab-detail { display: none; grid-column: 1 / -1; margin-top: 0.5rem; padding-top: 0.5rem; border-top: 1px solid var(--border); }
.vocab-card.expanded .vocab-detail { display: block; }
.vocab-pos { display: inline-block; font-size: 0.7rem; background: var(--blue-bg); color: var(--blue); padding: 0.1rem 0.4rem; border-radius: 3px; font-weight: 600; margin-right: 0.3rem; }
.vocab-topic { display: inline-block; font-size: 0.7rem; background: var(--gold-bg); color: var(--gold); padding: 0.1rem 0.4rem; border-radius: 3px; margin-right: 0.2rem; }
.vocab-example { margin-top: 0.5rem; padding: 0.5rem 0.65rem; background: var(--bg); border-radius: 6px; font-size: 0.85rem; }
.vocab-example .ex-hz { font-family: var(--font-zh); font-size: 1rem; }
.vocab-example .ex-py { color: var(--accent); font-size: 0.82rem; }
.vocab-example .ex-vi { color: var(--ink-2); font-size: 0.82rem; }
.vocab-example + .vocab-example { margin-top: 0.3rem; }
.play-btn { background: none; border: none; cursor: pointer; font-size: 1rem; padding: 0.15rem 0.3rem; border-radius: 4px; transition: background var(--transition); }
.play-btn:hover { background: var(--accent-light); }

/* === Grammar === */
.grammar-count { font-size: 0.82rem; color: var(--ink-3); margin-bottom: 1rem; }
.grammar-cat { margin-bottom: 1.5rem; }
.grammar-cat-title { font-size: 0.88rem; font-weight: 700; color: var(--ink-2); margin-bottom: 0.6rem; padding: 0.3rem 0; border-bottom: 1px solid var(--border); display: flex; align-items: center; gap: 0.5rem; }
.grammar-cat-count { font-size: 0.72rem; font-weight: 600; background: var(--accent-light); color: var(--accent); padding: 0.1rem 0.45rem; border-radius: 10px; }
.grammar-list { display: flex; flex-direction: column; gap: 0.4rem; }
.grammar-card {
  background: var(--bg-card); border: 1px solid var(--border); border-radius: 8px;
  padding: 0.7rem 0.9rem; cursor: pointer; transition: border var(--transition);
}
.grammar-card:hover { border-color: var(--accent); }
.grammar-card.expanded { border-color: var(--accent); box-shadow: var(--shadow); }
.grammar-head { display: flex; align-items: baseline; gap: 0.6rem; flex-wrap: wrap; }
.grammar-pattern { font-family: var(--font-zh); font-size: 1rem; font-weight: 600; color: var(--accent); flex-shrink: 0; }
.grammar-title { font-size: 0.85rem; color: var(--ink-2); flex: 1; }
.grammar-chevron { font-size: 0.7rem; color: var(--ink-3); transition: transform 0.2s ease; flex-shrink: 0; }
.grammar-card.expanded .grammar-chevron { transform: rotate(90deg); color: var(--accent); }
.grammar-body {
  max-height: 0; overflow: hidden; transition: max-height 0.3s ease;
}
.grammar-card.expanded .grammar-body { max-height: 2000px; }
.grammar-explanation { font-size: 0.88rem; color: var(--ink); line-height: 1.65; margin-top: 0.7rem; padding-top: 0.7rem; border-top: 1px solid var(--border); }
.grammar-explanation p { margin-bottom: 0.5rem; }
.grammar-explanation p:last-child { margin-bottom: 0; }
.grammar-examples-label { font-size: 0.78rem; font-weight: 600; color: var(--ink-3); margin-top: 0.7rem; margin-bottom: 0.3rem; text-transform: uppercase; letter-spacing: 0.05em; }
.grammar-example { padding: 0.5rem 0.65rem; background: var(--bg); border-radius: 6px; font-size: 0.85rem; margin-bottom: 0.3rem; }
.grammar-example .ex-hz { font-family: var(--font-zh); font-size: 1rem; }
.grammar-example .ex-py { color: var(--accent); font-size: 0.82rem; }
.grammar-example .ex-vi { color: var(--ink-2); font-size: 0.82rem; }

/* Pagination */
.load-more { display: block; margin: 1rem auto; padding: 0.5rem 2rem; background: var(--accent-light); color: var(--accent); border: 1px solid var(--accent); border-radius: 8px; font-weight: 600; cursor: pointer; transition: all var(--transition); }
.load-more:hover { background: var(--accent); color: #fff; }

/* === Responsive === */
@media (max-width: 640px) {
  .top-bar-inner { flex-wrap: wrap; padding: 0.4rem 0.75rem; gap: 0.5rem; }
  .search-box { max-width: none; order: 3; flex-basis: 100%; }
  .top-stats { display: none; }
  .hero-mascot { width: 80px; }
  .hero h1 { font-size: 1.25rem; }
  .stats-bar { gap: 1rem; }
  .level-grid { grid-template-columns: 1fr; }
  main { padding: 1rem 0.75rem 2rem; }
  .lesson-row { padding: 0.5rem 0.4rem; }
  .vocab-card { grid-template-columns: auto 1fr; }
  .vocab-vi { grid-column: 1 / -1; text-align: left; }
}