:root {
  --bg: #faf7f2;
  --card: #ffffff;
  --text: #2b2b2b;
  --muted: #777;
  --accent: #c0392b;
  --border: #e6e0d6;
  --known: #2e8b57;
  --known-soft: #dff1e6;
  --learning: #b7860b;
  --learning-soft: #fbf0d0;
}

/* Dark theme: follows the system setting unless the viewer explicitly picked light or dark */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #1c1b1a;
    --card: #262523;
    --text: #eeeae4;
    --muted: #a09a92;
    --accent: #e8665a;
    --border: #3a3835;
    --known: #5cc98a;
    --known-soft: #1f3a2a;
    --learning: #e0b340;
    --learning-soft: #3d3218;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #1c1b1a;
  --card: #262523;
  --text: #eeeae4;
  --muted: #a09a92;
  --accent: #e8665a;
  --border: #3a3835;
  --known: #5cc98a;
  --known-soft: #1f3a2a;
  --learning: #e0b340;
  --learning-soft: #3d3218;
  color-scheme: dark;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, "Segoe UI", "Microsoft YaHei", sans-serif;
}

header {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 8px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
}

h1 { font-size: 1.2rem; margin: 0; }
h2 { font-size: 1rem; color: var(--muted); margin: 0 0 8px; }

.controls { display: flex; flex-wrap: wrap; gap: 16px; font-size: 0.9rem; align-items: center; }

select {
  font: inherit;
  padding: 4px 6px;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text);
}

main { max-width: 640px; margin: 0 auto; padding: 16px; }

.muted { color: var(--muted); }

.warning {
  background: #fff3cd;
  color: #664d03;
  padding: 10px 12px;
  border-radius: 8px;
  font-size: 0.9rem;
}

button {
  font: inherit;
  padding: 8px 16px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text);
  cursor: pointer;
}
button:hover { border-color: var(--accent); }
button.small { padding: 4px 10px; font-size: 0.85rem; }

/* ---------- Progress ---------- */

.progress { margin-bottom: 16px; font-size: 0.9rem; }

.progress-line {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 8px;
}
.progress-actions { display: flex; gap: 6px; }

.bar {
  height: 8px;
  background: var(--border);
  border-radius: 4px;
  overflow: hidden;
  margin: 8px 0 4px;
}
.bar-fill { height: 100%; width: 0; background: var(--known); transition: width 0.3s; }

.phrase-stats { color: var(--muted); font-size: 0.85rem; }

.legend { display: flex; flex-wrap: wrap; gap: 12px; margin: 12px 0 8px; font-size: 0.8rem; }
.dot {
  display: inline-block;
  width: 10px; height: 10px;
  border-radius: 3px;
  margin-right: 4px;
  border: 1px solid var(--border);
  background: var(--card);
  vertical-align: -1px;
}
.dot.known { background: var(--known); border-color: var(--known); }
.dot.learning { background: var(--learning); border-color: var(--learning); }

.char-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(36px, 1fr));
  gap: 4px;
}
.grid-char {
  padding: 4px 0;
  font-size: 1.1rem;
  font-family: "Microsoft YaHei", "PingFang SC", "Noto Sans SC", sans-serif;
}
.grid-note { color: var(--muted); font-size: 0.85rem; min-height: 1em; margin: 8px 0 0; }
.grid-char.known { background: var(--known-soft); border-color: var(--known); }
.grid-char.learning { background: var(--learning-soft); border-color: var(--learning); }

/* ---------- Phrase card ---------- */

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 20px 16px 24px;
  text-align: center;
}

.card-top { display: flex; justify-content: space-between; align-items: center; }
.counter { color: var(--muted); font-size: 0.85rem; }

.badge {
  font-size: 0.75rem;
  padding: 2px 8px;
  border-radius: 999px;
  border: 1px solid var(--border);
  color: var(--muted);
}
.badge.known { color: var(--known); border-color: var(--known); }
.badge.learning { color: var(--learning); border-color: var(--learning); }

.hanzi {
  display: block;
  margin: 4px auto;
  background: none;
  border: none;
  color: var(--text);
  font-size: 5rem;
  font-family: "Microsoft YaHei", "PingFang SC", "Noto Sans SC", sans-serif;
  cursor: pointer;
}

.phrase-rank { color: var(--muted); font-size: 0.8rem; min-height: 1em; margin-bottom: 8px; }

.pinyin { font-size: 1.6rem; color: var(--accent); }
.meaning { font-size: 1.2rem; margin-top: 4px; }

.reveal.hidden { visibility: hidden; }

.breakdown {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 16px;
}

.char-tile {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  width: 140px;
  padding: 10px 8px;
  background: var(--bg);
}
.ct-char { font-size: 2rem; font-family: "Microsoft YaHei", "PingFang SC", "Noto Sans SC", sans-serif; }
.ct-pinyin { color: var(--accent); }
.ct-meaning { font-size: 0.8rem; line-height: 1.3; }
.ct-rank { font-size: 0.7rem; color: var(--muted); margin-top: 2px; }

.show-answer, .card-actions { margin-top: 16px; }

.mark { display: flex; justify-content: center; gap: 10px; margin-top: 12px; }
.learning-btn.active { background: var(--learning-soft); border-color: var(--learning); }
.known-btn.active { background: var(--known-soft); border-color: var(--known); }
.learning-btn:hover { border-color: var(--learning); }
.known-btn:hover { border-color: var(--known); }

/* ---------- Examples ---------- */

.examples { margin-top: 24px; }
.examples ol { padding-left: 0; list-style: none; margin: 0; }

.examples li {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 12px;
  margin-bottom: 10px;
}

.examples li button { padding: 4px 10px; flex-shrink: 0; }
.ex-zh { font-size: 1.25rem; }
.ex-zh mark { background: none; color: var(--accent); font-weight: 600; }
.ex-pinyin { color: var(--muted); font-size: 0.95rem; }
.ex-en { font-size: 0.95rem; margin-top: 2px; }

.nav { display: flex; justify-content: space-between; margin-top: 16px; }
.hint { text-align: center; color: var(--muted); font-size: 0.8rem; }