:root {
  --bg: #faf7f0;
  --surface: #ffffff;
  --text: #2b2724;
  --muted: #7a726a;
  --line: #e8e1d5;
  --accent: #b5442f;
  --accent-soft: #f6e4dd;
  --link: #2f5d8a;
  --grid: #d9534f;
  --grid-dash: #f0b8b3;
  --tzg-bg: #fffdf8;

  --kai: "KaiTi", "STKaiti", "Kaiti SC", "楷体", "FandolKai", "AR PL KaitiM GB", "AR PL UKai CN", "LXGW WenKai", serif;
  --sans: system-ui, -apple-system, "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  --latin: "Helvetica Neue", Arial, sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1d1b19;
    --surface: #26231f;
    --text: #ece6dc;
    --muted: #a39a8e;
    --line: #3a352f;
    --accent: #e58a73;
    --accent-soft: #3d2a24;
    --link: #8fb8e0;
    --grid: #c4675b;
    --grid-dash: #5a3a35;
    --tzg-bg: #2a2622;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  line-height: 1.6;
}

a { color: var(--link); text-decoration: none; }
a:hover { color: var(--accent); }

.wrap { max-width: 960px; margin: 0 auto; padding: 0 16px; }
main.wrap { padding-bottom: 48px; }

h1 { font-size: 1.8rem; margin: 0.4em 0 0.3em; }
h2 { font-size: 1.15rem; margin: 1.6em 0 0.6em; }
section { margin-bottom: 8px; }

.muted { color: var(--muted); }
.label { color: var(--muted); font-size: 0.9rem; margin: 0.8em 0 0.4em; }
.lede { color: var(--muted); margin-top: 0; }

/* Header, breadcrumbs, footer */

header.site {
  background: var(--surface);
  border-bottom: 1px solid var(--line);
}
header.site .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 52px;
}
.brand {
  font-family: var(--kai);
  font-size: 1.4rem;
  color: var(--accent);
}
header.site nav a { margin-left: 20px; color: var(--text); }
header.site nav a:hover { color: var(--accent); }

.crumbs { margin-top: 16px; font-size: 0.9rem; color: var(--muted); }

.progress {
  background: var(--accent-soft);
  border-radius: 8px;
  padding: 8px 12px;
  font-size: 0.9rem;
}
.progress a:last-child { margin-left: 8px; }

footer.site {
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.85rem;
  padding: 16px 0 24px;
}

/* Buttons */

.btn, .toggle {
  display: inline-block;
  min-width: 2.4em;
  padding: 4px 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--text);
  font: inherit;
  text-align: center;
  cursor: pointer;
}
.btn:hover, .toggle:hover { border-color: var(--accent); color: var(--accent); }
.btn.small { font-size: 0.85rem; font-weight: normal; padding: 2px 10px; margin-left: 8px; }
.btn.wide { margin-top: 24px; }

.toggle .off { display: none; }
.hide-py .toggle .on { display: none; }
.hide-py .toggle .off { display: inline; }

.section-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin: 1.6em 0 0.6em;
}
.section-head h1, .section-head h2 { margin: 0; }

/* Home and book pages */

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 16px;
  margin-top: 24px;
}
.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 16px 20px 20px;
}
.card h2 { margin: 0; font-size: 1.3rem; }
.card .muted { margin: 0; }
.units {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
}

.unit h2 { display: flex; align-items: center; }
.lessons {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 8px;
}
.lessons a {
  display: block;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 10px 14px;
  color: var(--text);
}
.lessons a:hover { border-color: var(--accent); }
.lessons .title { display: block; }
.lessons .preview {
  display: block;
  font-family: var(--kai);
  font-size: 1.15rem;
  color: var(--muted);
  letter-spacing: 0.15em;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* Characters in 田字格 */

.grid { display: flex; flex-wrap: wrap; gap: 10px 8px; }

.tzg {
  --s: 64px;
  display: flex;
  align-items: center;
  justify-content: center;
  width: var(--s);
  height: var(--s);
  border: 1.5px solid var(--grid);
  background:
    linear-gradient(to right, transparent calc(50% - 0.5px), var(--grid-dash) calc(50% - 0.5px), var(--grid-dash) calc(50% + 0.5px), transparent calc(50% + 0.5px)),
    linear-gradient(to bottom, transparent calc(50% - 0.5px), var(--grid-dash) calc(50% - 0.5px), var(--grid-dash) calc(50% + 0.5px), transparent calc(50% + 0.5px)),
    var(--tzg-bg);
  font-family: var(--kai);
  font-size: calc(var(--s) * 0.74);
  line-height: 1;
  color: var(--text);
}
.tzg.big { --s: 128px; border-width: 2px; }

.zi {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
}
.zi .py {
  font-family: var(--latin);
  font-size: 0.95rem;
  color: var(--muted);
  min-height: 1.5em;
  white-space: nowrap;
}
.zi:hover .tzg { border-color: var(--accent); background-color: var(--accent-soft); }
.zi:hover .py { color: var(--accent); }
.zi.small .tzg { --s: 48px; }
.zi.small .py { font-size: 0.8rem; }
.zi.current .tzg { background-color: var(--accent-soft); }

.hide-py .zi .py { visibility: hidden; }

/* Character page */

.hero {
  display: flex;
  align-items: center;
  gap: 24px;
  margin: 20px 0 8px;
}
.hero-py { font-family: var(--latin); font-size: 2rem; margin: 0; }
.hero .muted { margin: 0; }

.reading {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 12px 16px;
  margin-bottom: 12px;
}
.reading > .muted { margin: 4px 0 0; font-size: 0.9rem; }

.py-tag {
  display: inline-block;
  font-family: var(--latin);
  font-size: 1.4rem;
  min-width: 3.5em;
}
.py-tag.small { font-size: 1.1rem; }
.py-title { font-family: var(--latin); }

.part-name { font-family: var(--kai); font-size: 1.4rem; }

.chips { display: flex; flex-wrap: wrap; gap: 6px; }
.chip {
  display: inline-block;
  font-family: var(--kai);
  font-size: 1.6rem;
  line-height: 1;
  padding: 6px 8px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--text);
}
.chip:hover { border-color: var(--accent); color: var(--accent); }

/* Words */

.words {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 4px 6px;
  font-family: var(--kai);
  font-size: 1.25rem;
}
.words li {
  padding: 0 8px;
  border-radius: 6px;
  background: var(--surface);
  border: 1px solid var(--line);
}

.word-row {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  padding: 10px 0;
  border-bottom: 1px solid var(--line);
}
.word-row .words-wrap, .word-row > .muted { margin-top: 1.6em; }

.more-words summary {
  margin-top: 6px;
  color: var(--muted);
  font-size: 0.9rem;
  cursor: pointer;
}
.more-words summary:hover { color: var(--accent); }
.more-words .words { margin-top: 6px; }

/* Pinyin pages */

.tone-row {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 6px 0;
}
.stems { columns: 280px; column-gap: 12px; }
.stem {
  break-inside: avoid;
  margin-bottom: 12px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 4px 14px 10px;
}
.stem h2 { font-family: var(--latin); margin: 0.4em 0 0.2em; }
.stem .chip { font-size: 1.3rem; padding: 4px 6px; }

/* Lesson pager */

.pager {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 32px;
}
.pager a {
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 8px 14px;
  background: var(--surface);
}

@media (max-width: 600px) {
  h1 { font-size: 1.5rem; }
  .tzg.big { --s: 96px; }
  .word-row { gap: 10px; }
  header.site nav a { margin-left: 14px; }
}

@media print {
  header.site, footer.site, .toggle, .pager, .progress { display: none; }
  body { background: #fff; color: #000; }
  .grid { gap: 6px; }
}