:root {
  --bg: #faf7f2;
  --card: #ffffff;
  --ink: #2a2420;
  --muted: #7a6f64;
  --line: #ece5da;
  --accent: #c2410c;      /* warm terracotta */
  --accent-soft: #fde7d8;
  --good: #16a34a;
  --good-soft: #dcfce7;
  --shadow: 0 1px 3px rgba(0,0,0,.06), 0 6px 20px rgba(0,0,0,.04);
  --radius: 14px;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.65;
}

/* Chinese text reads larger for clarity */
.zh { font-size: 1.18rem; line-height: 1.9; }

/* ---- Layout ---- */
header.topbar {
  position: sticky; top: 0; z-index: 20;
  background: rgba(250,247,242,.92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
.topbar-inner {
  max-width: 920px; margin: 0 auto; padding: 12px 18px;
  display: flex; align-items: center; gap: 14px; flex-wrap: wrap;
}
.brand { font-weight: 700; font-size: 1.05rem; color: var(--accent); white-space: nowrap; }
.brand small { color: var(--muted); font-weight: 400; margin-left: 6px; }
nav.tabs { display: flex; gap: 4px; flex-wrap: wrap; }
nav.tabs a {
  text-decoration: none; color: var(--muted);
  padding: 6px 11px; border-radius: 999px; font-size: .92rem; white-space: nowrap;
}
nav.tabs a:hover { background: var(--accent-soft); color: var(--accent); }
nav.tabs a.active { background: var(--accent); color: #fff; }

main { max-width: 920px; margin: 0 auto; padding: 22px 18px 80px; }

h1 { font-size: 1.5rem; margin: .2em 0 .6em; }
h2 { font-size: 1.2rem; margin: 1.4em 0 .5em; }
h3 { font-size: 1.02rem; margin: 1.1em 0 .4em; color: var(--muted); text-transform: none; letter-spacing: .02em; }
p { margin: .5em 0; }
.muted { color: var(--muted); }

/* ---- Cards ---- */
.card {
  background: var(--card); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 18px; box-shadow: var(--shadow);
}
.grid { display: grid; gap: 14px; }
.grid.cols-2 { grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); }
.grid.cols-3 { grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); }

.topic-card { cursor: pointer; transition: transform .08s ease, box-shadow .12s ease; }
.topic-card:hover { transform: translateY(-2px); box-shadow: 0 10px 28px rgba(0,0,0,.08); }
.topic-card .icon { font-size: 1.8rem; }
.topic-card .title { font-weight: 600; font-size: 1.1rem; margin: 6px 0 2px; }

.tag {
  display: inline-block; font-size: .76rem; padding: 2px 9px; border-radius: 999px;
  background: var(--accent-soft); color: var(--accent); margin-right: 6px;
}
.tag.done { background: var(--good-soft); color: var(--good); }

/* ---- Buttons ---- */
button, .btn {
  font: inherit; cursor: pointer; border: 1px solid var(--line);
  background: var(--card); color: var(--ink);
  padding: 9px 15px; border-radius: 10px; transition: background .1s;
}
button:hover, .btn:hover { background: var(--accent-soft); }
button.primary, .btn.primary { background: var(--accent); color: #fff; border-color: var(--accent); }
button.primary:hover { background: #a8350a; }
button.ghost { background: transparent; }
button:disabled { opacity: .5; cursor: default; }
.row { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }

/* ---- Phrase rows ---- */
.phrase {
  display: flex; align-items: flex-start; gap: 12px;
  padding: 12px 0; border-bottom: 1px solid var(--line);
}
.phrase:last-child { border-bottom: none; }
.phrase .body { flex: 1; }
.phrase .zh { margin: 0; }
.phrase .pinyin { color: var(--muted); font-size: .88rem; font-style: italic; }
.phrase .en { color: var(--muted); font-size: .9rem; }
.speak-btn { font-size: 1.2rem; line-height: 1; padding: 8px 10px; }
.learn-btn { white-space: nowrap; }

/* ---- Hints ---- */
.hint {
  background: #fff8f1; border-left: 3px solid var(--accent);
  padding: 10px 14px; border-radius: 0 8px 8px 0; margin: 8px 0;
}

/* ---- Countdown ---- */
.countdown { display: flex; align-items: baseline; gap: 10px; }
.countdown .num { font-size: 2.6rem; font-weight: 800; color: var(--accent); line-height: 1; }

/* ---- Timer ---- */
.timer-display { font-size: 4rem; font-weight: 800; text-align: center; font-variant-numeric: tabular-nums; }
.timer-display.warn { color: var(--accent); }
.timer-display.done { color: var(--good); }
.scaffold { white-space: pre-wrap; background: #fff8f1; padding: 14px 16px; border-radius: 10px; line-height: 2.1; }

/* ---- Progress bars ---- */
.bar { height: 10px; background: var(--line); border-radius: 999px; overflow: hidden; }
.bar > span { display: block; height: 100%; background: var(--accent); }

label { display: block; font-size: .9rem; color: var(--muted); margin: 10px 0 4px; }
input[type=range] { width: 100%; }
textarea, input[type=text] {
  width: 100%; font: inherit; padding: 9px 11px; border: 1px solid var(--line);
  border-radius: 10px; background: #fff; color: var(--ink);
}
.notice { background: var(--accent-soft); color: var(--accent); padding: 10px 14px; border-radius: 10px; font-size: .9rem; }
ul.clean { padding-left: 1.2em; }
ul.clean li { margin: .35em 0; }
.back { display: inline-block; margin-bottom: 8px; color: var(--accent); text-decoration: none; }