:root {
  --bg: #f4f6f9;
  --surface: #ffffff;
  --surface-2: #f8fafc;
  --border: #e2e8f0;
  --border-strong: #cbd5e1;
  --text: #0f172a;
  --text-2: #475569;
  --text-3: #94a3b8;
  --primary: #1f5fbf;
  --primary-hover: #1a50a3;
  --primary-soft: #e8f0fc;
  --ok: #15803d;
  --ok-soft: #e7f6ec;
  --bad: #c2410c;
  --bad-soft: #fdf0e8;
  --warn: #a16207;
  --warn-soft: #fdf6e3;
  --flag: #7c3aed;
  --radius: 10px;
  --shadow: 0 1px 2px rgba(15, 23, 42, 0.06), 0 2px 8px rgba(15, 23, 42, 0.04);
  --font: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang TC', 'Microsoft JhengHei', 'Noto Sans TC', sans-serif;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme='light']) {
    --bg: #0d1117;
    --surface: #161b22;
    --surface-2: #1c2230;
    --border: #2a3140;
    --border-strong: #3a4354;
    --text: #e6edf3;
    --text-2: #a7b3c2;
    --text-3: #6b7685;
    --primary: #5b9cf5;
    --primary-hover: #77aef7;
    --primary-soft: #1a2a44;
    --ok: #4ade80;
    --ok-soft: #12301f;
    --bad: #fb923c;
    --bad-soft: #3a2113;
    --warn: #facc15;
    --warn-soft: #36300f;
    --flag: #a78bfa;
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  background: var(--bg);
  color: var(--text);
  font: 15px/1.6 var(--font);
  -webkit-font-smoothing: antialiased;
}
a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }
img { max-width: 100%; }
h1, h2, h3 { line-height: 1.3; margin: 0 0 12px; }
h1 { font-size: 22px; }
h2 { font-size: 18px; }
h3 { font-size: 16px; }
.muted { color: var(--text-2); }
.small { font-size: 13px; }
.hidden { display: none !important; }
.mono { font-family: var(--mono); }

/* ── 版面 ── */
.topbar {
  position: sticky; top: 0; z-index: 20;
  display: flex; align-items: center; gap: 16px;
  padding: 0 20px; height: 56px;
  background: var(--surface); border-bottom: 1px solid var(--border);
}
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; color: var(--text); }
.brand img { width: 26px; height: 26px; }
.brand:hover { text-decoration: none; }
.nav { display: flex; gap: 4px; flex: 1; }
.nav a { padding: 6px 12px; border-radius: 8px; color: var(--text-2); font-weight: 500; }
.nav a:hover { background: var(--surface-2); text-decoration: none; }
.nav a.active { background: var(--primary-soft); color: var(--primary); }
.user-box { display: flex; align-items: center; gap: 10px; color: var(--text-2); font-size: 14px; }
.container { max-width: 1120px; margin: 0 auto; padding: 24px 20px 64px; }
.container.narrow { max-width: 860px; }

.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow); padding: 20px;
}
.card + .card { margin-top: 16px; }
.grid { display: grid; gap: 16px; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr)); }
.row { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.row.between { justify-content: space-between; }
.stack > * + * { margin-top: 12px; }
.spacer { flex: 1; }

/* ── 按鈕與表單 ── */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  padding: 8px 16px; border-radius: 8px; border: 1px solid var(--border-strong);
  background: var(--surface); color: var(--text); font: inherit; font-weight: 500;
  cursor: pointer; white-space: nowrap; transition: background 0.12s, border-color 0.12s;
}
.btn:hover { background: var(--surface-2); text-decoration: none; }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }
.btn.primary { background: var(--primary); border-color: var(--primary); color: #fff; }
.btn.primary:hover { background: var(--primary-hover); }
.btn.danger { color: var(--bad); border-color: color-mix(in srgb, var(--bad) 40%, var(--border)); }
.btn.danger:hover { background: var(--bad-soft); }
.btn.ghost { border-color: transparent; background: transparent; }
.btn.ghost:hover { background: var(--surface-2); }
.btn.sm { padding: 4px 10px; font-size: 13px; }
.btn.lg { padding: 11px 22px; font-size: 16px; }

label.field { display: block; }
label.field > span { display: block; font-size: 13px; font-weight: 600; color: var(--text-2); margin-bottom: 4px; }
input[type='text'], input[type='password'], input[type='number'], input[type='search'], select, textarea {
  width: 100%; padding: 8px 10px; border-radius: 8px;
  border: 1px solid var(--border-strong); background: var(--surface); color: var(--text);
  font: inherit;
}
textarea { resize: vertical; min-height: 80px; }
input:focus, select:focus, textarea:focus, .btn:focus-visible {
  outline: 2px solid color-mix(in srgb, var(--primary) 50%, transparent); outline-offset: 1px;
}
.check { display: inline-flex; align-items: center; gap: 6px; cursor: pointer; user-select: none; }
.check input { width: 16px; height: 16px; accent-color: var(--primary); }

.badge {
  display: inline-flex; align-items: center; padding: 1px 8px; border-radius: 999px;
  font-size: 12px; font-weight: 600; background: var(--surface-2); color: var(--text-2);
  border: 1px solid var(--border);
}
.badge.ok { background: var(--ok-soft); color: var(--ok); border-color: transparent; }
.badge.bad { background: var(--bad-soft); color: var(--bad); border-color: transparent; }
.badge.warn { background: var(--warn-soft); color: var(--warn); border-color: transparent; }
.badge.primary { background: var(--primary-soft); color: var(--primary); border-color: transparent; }

.alert { padding: 10px 14px; border-radius: 8px; background: var(--warn-soft); color: var(--warn); font-size: 14px; }
.alert.bad { background: var(--bad-soft); color: var(--bad); }
.alert.ok { background: var(--ok-soft); color: var(--ok); }
.alert.info { background: var(--primary-soft); color: var(--primary); }

/* ── 表格 ── */
.table-wrap { overflow-x: auto; }
table.table { width: 100%; border-collapse: collapse; font-size: 14px; }
.table th, .table td { padding: 10px 12px; border-bottom: 1px solid var(--border); text-align: left; vertical-align: middle; }
.table th { font-size: 12px; font-weight: 600; color: var(--text-2); background: var(--surface-2); white-space: nowrap; }
.table tr:last-child td { border-bottom: none; }
.table td.num, .table th.num { text-align: right; font-variant-numeric: tabular-nums; }

/* ── 登入 ── */
.auth-wrap { min-height: 100vh; display: grid; place-items: center; padding: 20px; }
.auth-card { width: 100%; max-width: 380px; }
.turnstile:empty { display: none; }
.turnstile { display: flex; justify-content: center; min-height: 65px; }
.auth-card .brand { justify-content: center; font-size: 20px; margin-bottom: 20px; }

/* ── 題庫卡片 ── */
.bank-card { display: flex; flex-direction: column; gap: 14px; }
.bank-card h2 { margin: 0; }
.stat-row { display: flex; gap: 20px; flex-wrap: wrap; }
.stat { display: flex; flex-direction: column; }
.stat b { font-size: 20px; font-variant-numeric: tabular-nums; }
.stat span { font-size: 12px; color: var(--text-2); }
.bank-actions { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; }

/* ── 作答畫面 ── */
.quiz { display: grid; grid-template-columns: 1fr 260px; gap: 20px; align-items: start; }
.quiz-side { position: sticky; top: 76px; }
.quiz-head { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; margin-bottom: 14px; }
.q-body { font-size: 15.5px; }
.q-body .text { white-space: pre-wrap; margin: 0 0 12px; }
.q-body .img, .reveal .img { display: block; margin: 0 0 12px; border: 1px solid var(--border); border-radius: 6px; background: #fff; }
.img-group { margin-bottom: 12px; border: 1px solid var(--border); border-radius: 6px; overflow: hidden; background: #fff; width: fit-content; max-width: 100%; }
.img-group .img { display: block; margin: 0; border: none; border-radius: 0; }

.options { display: flex; flex-direction: column; gap: 8px; margin-top: 16px; }
.option {
  display: flex; gap: 12px; align-items: flex-start;
  padding: 12px 14px; border: 1.5px solid var(--border); border-radius: 10px;
  background: var(--surface); cursor: pointer; transition: border-color 0.12s, background 0.12s;
}
.option:hover { border-color: var(--border-strong); background: var(--surface-2); }
.option .key {
  flex: none; width: 28px; height: 28px; border-radius: 50%; display: grid; place-items: center;
  font-weight: 700; font-size: 13px; background: var(--surface-2); border: 1px solid var(--border-strong);
}
.option.selected { border-color: var(--primary); background: var(--primary-soft); }
.option.selected .key { background: var(--primary); color: #fff; border-color: var(--primary); }
.option.correct { border-color: var(--ok); background: var(--ok-soft); }
.option.correct .key { background: var(--ok); color: #fff; border-color: var(--ok); }
.option.wrong { border-color: var(--bad); background: var(--bad-soft); }
.option.wrong .key { background: var(--bad); color: #fff; border-color: var(--bad); }
.option.locked { cursor: default; }
.option .txt { padding-top: 2px; white-space: pre-wrap; }

.reveal { margin-top: 18px; padding: 16px; border-radius: 10px; background: var(--surface-2); border: 1px solid var(--border); }
.reveal h3 { margin-bottom: 8px; }
.reveal .expl { white-space: pre-wrap; font-size: 14px; color: var(--text-2); word-break: break-word; }
.result-banner { padding: 10px 14px; border-radius: 8px; font-weight: 600; margin-top: 16px; }
.result-banner.ok { background: var(--ok-soft); color: var(--ok); }
.result-banner.bad { background: var(--bad-soft); color: var(--bad); }

.quiz-nav { display: flex; gap: 10px; margin-top: 20px; align-items: center; flex-wrap: wrap; }
.timer { font-family: var(--mono); font-size: 22px; font-weight: 700; font-variant-numeric: tabular-nums; }
.timer.low { color: var(--bad); }
.palette { display: grid; grid-template-columns: repeat(auto-fill, minmax(36px, 1fr)); gap: 6px; margin-top: 12px; max-height: 50vh; overflow-y: auto; padding: 2px; }
.palette button {
  height: 34px; border-radius: 6px; border: 1px solid var(--border-strong);
  background: var(--surface); color: var(--text-2); font: 600 12px var(--font); cursor: pointer; position: relative;
}
.palette button.answered { background: var(--primary-soft); color: var(--primary); border-color: transparent; }
.palette button.correct { background: var(--ok-soft); color: var(--ok); border-color: transparent; }
.palette button.wrong { background: var(--bad-soft); color: var(--bad); border-color: transparent; }
.palette button.current { outline: 2px solid var(--primary); outline-offset: 1px; }
.palette button.flagged::after {
  content: ''; position: absolute; top: 3px; right: 3px; width: 6px; height: 6px; border-radius: 50%; background: var(--flag);
}
.legend { display: flex; flex-wrap: wrap; gap: 10px; font-size: 12px; color: var(--text-2); margin-top: 10px; }
.legend i { display: inline-block; width: 10px; height: 10px; border-radius: 3px; margin-right: 4px; vertical-align: -1px; }
.progress { height: 6px; border-radius: 999px; background: var(--surface-2); overflow: hidden; border: 1px solid var(--border); }
.progress > div { height: 100%; background: var(--primary); transition: width 0.2s; }

.score-big { font-size: 56px; font-weight: 800; line-height: 1; font-variant-numeric: tabular-nums; }

/* ── 對話框 ── */
.modal-back {
  position: fixed; inset: 0; z-index: 100; background: rgba(15, 23, 42, 0.45);
  display: grid; place-items: center; padding: 20px;
}
.modal {
  width: 100%; max-width: 520px; max-height: 90vh; overflow-y: auto;
  background: var(--surface); border-radius: 14px; box-shadow: 0 20px 50px rgba(0, 0, 0, 0.25); padding: 22px;
}
.modal.wide { max-width: 860px; }
.modal-foot { display: flex; justify-content: flex-end; gap: 8px; margin-top: 20px; }

.toast-box { position: fixed; bottom: 20px; left: 50%; transform: translateX(-50%); z-index: 200; display: flex; flex-direction: column; gap: 8px; align-items: center; }
.toast { padding: 10px 18px; border-radius: 8px; background: var(--text); color: var(--bg); font-size: 14px; box-shadow: var(--shadow); }
.toast.bad { background: var(--bad); color: #fff; }

.tabs { display: flex; gap: 4px; border-bottom: 1px solid var(--border); margin-bottom: 20px; }
.tabs button {
  padding: 10px 14px; border: none; background: none; font: inherit; font-weight: 600; color: var(--text-2);
  border-bottom: 2px solid transparent; margin-bottom: -1px; cursor: pointer;
}
.tabs button.active { color: var(--primary); border-bottom-color: var(--primary); }

.chips { display: flex; flex-wrap: wrap; gap: 6px; }
.chip { display: inline-flex; align-items: center; gap: 4px; padding: 3px 10px; border: 1px solid var(--border-strong); border-radius: 999px; font-size: 13px; cursor: pointer; user-select: none; }
.chip input { display: none; }
.chip:has(input:checked) { background: var(--primary-soft); border-color: var(--primary); color: var(--primary); }

.empty { text-align: center; padding: 48px 20px; color: var(--text-2); }
.kbd { font-family: var(--mono); font-size: 11px; padding: 1px 5px; border: 1px solid var(--border-strong); border-radius: 4px; color: var(--text-2); }

@media (max-width: 860px) {
  .quiz { grid-template-columns: 1fr; }
  .quiz-side { position: static; order: -1; }
  .palette { max-height: 140px; }
  .kbd-hint { display: none; }
  .nav a { padding: 6px 8px; }
  .user-box .name { display: none; }
}
@media (max-width: 520px) {
  .topbar { padding: 0 12px; gap: 8px; }
  .container { padding: 16px 12px 48px; }
  .brand span { display: none; }
  .bank-actions { grid-template-columns: 1fr; }
  .score-big { font-size: 44px; }
}