:root {
  --bg: #f6f1e7;
  --card: #fffdf8;
  --ink: #2a2723;
  --muted: #6d665c;
  --line: #e4dccd;
  --accent: #2f5d50;
  --accent-soft: #dfeae5;
  --accent-ink: #fdf8ee;
  --good: #2e7d4f;
  --good-soft: #e0f0e6;
  --bad: #b3452f;
  --bad-soft: #f7e1db;
  --radius: 16px;
  --max: 560px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #191816;
    --card: #23211e;
    --ink: #eee8de;
    --muted: #b1a99d;
    --line: #38342f;
    --accent: #7fbfa9;
    --accent-soft: #24352f;
    --accent-ink: #14201c;
    --good: #7cc79a;
    --good-soft: #1f3327;
    --bad: #e58b75;
    --bad-soft: #3a2420;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "PingFang TC", "Noto Sans TC", "Microsoft JhengHei", sans-serif;
  font-size: 17px;
  line-height: 1.6;
}

.app { max-width: var(--max); margin: 0 auto; padding: 20px 16px 48px; }

.screen[hidden] { display: none; }

.brand { text-align: center; padding: 24px 0 16px; }
.eyebrow { margin: 0; color: var(--muted); font-size: 14px; letter-spacing: .1em; }
.brand h1 { margin: 4px 0; font-size: clamp(32px, 9vw, 44px); font-family: "Noto Serif TC", "Songti TC", serif; }
.sub { margin: 0; color: var(--muted); }

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px;
}

.field { display: block; border: 0; padding: 0; margin: 0 0 16px; }
.field > span, .field legend { display: block; font-weight: 600; margin-bottom: 6px; }
select {
  width: 100%;
  font: inherit;
  color: inherit;
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 10px 12px;
}

.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chips label { cursor: pointer; }
.chips input { position: absolute; opacity: 0; pointer-events: none; }
.chips span {
  display: inline-block;
  padding: 8px 16px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: var(--bg);
}
.chips input:checked + span { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.chips input:focus-visible + span { outline: 2px solid var(--accent); outline-offset: 2px; }

.info { color: var(--muted); font-size: 15px; min-height: 1.6em; margin: 4px 0 12px; }
.source { color: var(--muted); font-size: 13px; text-align: center; margin: 14px 8px 0; }

.btn {
  font: inherit;
  font-weight: 600;
  border-radius: 12px;
  border: 1px solid var(--line);
  background: var(--bg);
  color: var(--ink);
  padding: 12px 18px;
  cursor: pointer;
  width: 100%;
}
.btn.primary { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.btn.ghost { background: transparent; }
.btn.small { width: auto; padding: 6px 12px; font-size: 15px; }
.btn:disabled { opacity: .45; cursor: not-allowed; }

/* Quiz */
.topbar { display: flex; align-items: center; gap: 10px; margin-bottom: 10px; }
.lesson-name { flex: 1; text-align: center; color: var(--muted); font-size: 15px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.score { font-weight: 700; color: var(--accent); }

.progress { height: 6px; background: var(--line); border-radius: 999px; overflow: hidden; margin-bottom: 14px; }
#progress-bar { height: 100%; width: 0; background: var(--accent); transition: width .3s; }

.q-type { margin: 0; font-size: 14px; color: var(--accent); font-weight: 700; letter-spacing: .08em; }
.q-prompt { font-size: 20px; margin: 6px 0 4px; }
.q-context { color: var(--muted); margin: 0 0 16px; font-size: 16px; }

.word-big { font-family: "Noto Serif TC", "Songti TC", serif; font-size: 40px; letter-spacing: .08em; }
.word-big mark { background: var(--accent-soft); color: var(--accent); border-radius: 6px; padding: 0 2px; }
.blank { display: inline-block; min-width: 1.1em; border-bottom: 3px solid var(--accent); color: transparent; }
.zhuyin { font-size: 18px; color: var(--muted); letter-spacing: .1em; }

.options { display: grid; gap: 10px; }
.options.grid2 { grid-template-columns: 1fr 1fr; }
.option {
  font: inherit;
  text-align: left;
  padding: 14px 16px;
  border-radius: 12px;
  border: 2px solid var(--line);
  background: var(--bg);
  color: var(--ink);
  cursor: pointer;
}
.options.grid2 .option { text-align: center; font-size: 26px; font-family: "Noto Serif TC", "Songti TC", serif; }
.option:hover:not(:disabled) { border-color: var(--accent); }
.option.correct { border-color: var(--good); background: var(--good-soft); }
.option.wrong { border-color: var(--bad); background: var(--bad-soft); }
.option:disabled { cursor: default; }

.feedback { margin: 14px 0; padding: 12px 14px; border-radius: 12px; background: var(--accent-soft); }
.feedback b { display: block; margin-bottom: 2px; }
.feedback.good b { color: var(--good); }
.feedback.bad b { color: var(--bad); }
.feedback p { margin: 0; }

/* Result */
.result { text-align: center; }
.big-score { font-size: 56px; font-weight: 800; margin: 4px 0; color: var(--accent); }
.comment { margin: 0 0 16px; }
#result-review { text-align: left; margin-bottom: 16px; }
.review-item { border-top: 1px dashed var(--line); padding: 10px 0; }
.review-item:first-child { border-top: 0; }
.review-item .w { font-family: "Noto Serif TC", "Songti TC", serif; font-size: 22px; }
.review-item .z { color: var(--muted); font-size: 15px; margin-left: 6px; }
.review-item p { margin: 2px 0 0; font-size: 15px; color: var(--muted); }
.actions { display: grid; gap: 10px; }