:root {
  --bg: #eef1f5; --card: #fff; --ink: #1d2733; --muted: #5b6776; --line: #cfd6df;
  --brand: #123d6a; --brand-ink: #fff; --accent: #1f6fb5;
  --ok: #1d7a3a; --ok-bg: #e5f4ea; --ng: #b3261e; --ng-bg: #fbe9e7;
  --mark: #e0a100; --mark-bg: #fff4d1; --cur: #1f6fb5;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12161c; --card: #1b222b; --ink: #e4e9ef; --muted: #9aa6b4; --line: #333f4c;
    --brand: #0d2a4a; --accent: #6aa9e9;
    --ok: #6fd08e; --ok-bg: #173523; --ng: #ff8a80; --ng-bg: #3a1c1a;
    --mark: #ffc94a; --mark-bg: #3a3014; --cur: #6aa9e9;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0; background: var(--bg); color: var(--ink);
  font-family: "Noto Sans TC", "Microsoft JhengHei", "PingFang TC", "Heiti TC", sans-serif;
  font-size: 17px; line-height: 1.7;
}
.topbar {
  position: sticky; top: 0; z-index: 5; display: flex; gap: 16px; align-items: center;
  padding: 8px 16px; background: var(--brand); color: var(--brand-ink); flex-wrap: wrap;
}
.brand { font-weight: 700; }
.tag { margin-left: 6px; font-size: 12px; padding: 1px 6px; border: 1px solid currentColor; border-radius: 4px; }
.examinfo { flex: 1; font-size: 15px; opacity: .9; min-width: 0; }
.timer { font-size: 16px; padding: 2px 10px; border-radius: 6px; background: rgba(255,255,255,.12); }
.timer b { font-variant-numeric: tabular-nums; font-size: 20px; }
.timer.warn { background: #b3261e; }
main { max-width: 1180px; margin: 0 auto; padding: 16px; }
.card { background: var(--card); border: 1px solid var(--line); border-radius: 8px; padding: 20px; margin-bottom: 16px; }
h1 { font-size: 22px; margin: 0 0 12px; }
h2 { font-size: 17px; margin: 0 0 10px; }
.meta { border-collapse: collapse; margin: 8px 0 12px; }
.meta th, .meta td { border: 1px solid var(--line); padding: 6px 12px; text-align: left; vertical-align: top; }
.meta th { white-space: nowrap; background: var(--bg); }
.notice { color: var(--muted); font-size: 15px; padding-left: 20px; }
.actions { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 12px; }
button {
  font: inherit; font-size: 16px; padding: 8px 16px; border-radius: 6px; cursor: pointer;
  border: 1px solid var(--line); background: var(--card); color: var(--ink);
}
button:hover:not(:disabled) { border-color: var(--accent); }
button:disabled { opacity: .45; cursor: default; }
button:focus-visible, input:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }
button.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
button.danger { background: var(--ng); border-color: var(--ng); color: #fff; }

.exam-layout { display: grid; grid-template-columns: minmax(0, 1fr) 300px; gap: 16px; align-items: start; }
.qhead { display: flex; align-items: baseline; gap: 6px; border-bottom: 1px solid var(--line); padding-bottom: 8px; }
.qno b { font-size: 22px; }
.qtotal { color: var(--muted); flex: 1; }
.markbox { color: var(--mark); font-weight: 600; cursor: pointer; white-space: nowrap; }
.qtext { font-size: 19px; margin: 16px 0; white-space: pre-wrap; }
.options { display: flex; flex-direction: column; gap: 10px; }
.opt {
  display: flex; gap: 10px; align-items: flex-start; padding: 10px 14px; cursor: pointer;
  border: 1px solid var(--line); border-radius: 6px;
}
.opt:hover { border-color: var(--accent); }
.opt.chosen { border-color: var(--accent); background: color-mix(in srgb, var(--accent) 12%, transparent); }
.opt input { margin-top: 7px; }
.letter { font-weight: 700; min-width: 2.2em; }
.qnav { display: flex; justify-content: space-between; gap: 8px; margin-top: 20px; flex-wrap: wrap; }
.navpane { position: sticky; top: 64px; }
.navgrid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 6px; }
.nav { padding: 6px 0; font-size: 15px; font-variant-numeric: tabular-nums; position: relative; }
.nav.answered { background: var(--ok-bg); border-color: var(--ok); }
.nav.marked { box-shadow: inset 0 -4px 0 var(--mark); background: var(--mark-bg); }
.nav.current { outline: 2px solid var(--cur); outline-offset: 1px; font-weight: 700; }
.legend { list-style: none; padding: 0; margin: 12px 0 4px; font-size: 13px; color: var(--muted); display: grid; grid-template-columns: 1fr 1fr; }
.sw { display: inline-block; width: 14px; height: 14px; border: 1px solid var(--line); border-radius: 3px; vertical-align: -2px; margin-right: 4px; }
.sw.answered { background: var(--ok-bg); border-color: var(--ok); }
.sw.marked { background: var(--mark-bg); border-color: var(--mark); }
.sw.current { outline: 2px solid var(--cur); }
.progress { font-size: 15px; }
#btn-submit { width: 100%; }
dialog { border: 1px solid var(--line); border-radius: 8px; background: var(--card); color: var(--ink); max-width: 420px; }
dialog::backdrop { background: rgba(0,0,0,.45); }

.score { text-align: center; }
.bigscore b { font-size: 56px; color: var(--accent); }
.filters { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 8px; }
.filters button.on { background: var(--accent); color: #fff; border-color: var(--accent); }
.review { padding-left: 0; list-style: none; }
.ritem { border-top: 1px solid var(--line); padding: 14px 0; }
.rhead { display: flex; gap: 12px; flex-wrap: wrap; font-size: 15px; color: var(--muted); align-items: center; }
.ritem .qtext { font-size: 17px; margin: 8px 0; }
.badge { font-size: 13px; padding: 1px 8px; border-radius: 10px; color: #fff; }
.badge.ok { background: var(--ok); } .badge.ng { background: var(--ng); } .badge.warn { background: var(--mark); color: #000; }
.ropts { list-style: none; padding-left: 0; margin: 0; }
.ropts li { padding: 3px 8px; border-radius: 4px; }
.ropts li.right { background: var(--ok-bg); color: var(--ok); font-weight: 600; }
.ropts li.yours { background: var(--ng-bg); color: var(--ng); text-decoration: line-through; }
.correction { color: var(--mark); font-weight: 600; font-size: 15px; }
.explain summary { cursor: pointer; color: var(--accent); font-weight: 600; margin-top: 6px; }
.extext { white-space: pre-wrap; background: var(--bg); padding: 10px 14px; border-radius: 6px; margin-top: 6px; font-size: 16px; }
.src { font-size: 13px; color: var(--muted); }
a { color: var(--accent); }
.optbtn { text-align: left; }
.empty { color: var(--muted); padding: 12px 0; }
.hint { color: var(--muted); font-size: 15px; }
footer { max-width: 1180px; margin: 0 auto; padding: 8px 16px 32px; font-size: 13px; color: var(--muted); }
[hidden] { display: none !important; }

@media (max-width: 820px) {
  body { font-size: 16px; }
  .exam-layout { grid-template-columns: 1fr; }
  .navpane { position: static; }
  .navgrid { grid-template-columns: repeat(10, 1fr); }
  .nav { font-size: 13px; padding: 4px 0; }
  .qtext { font-size: 17px; }
}

.site-nav { display:flex; flex-wrap:wrap; gap:12px 24px; padding:14px 20px; border-bottom:1px solid var(--line); background:var(--card,#fff); }
.site-nav a { font-size:15px; font-weight:650; }
.blur-preview { filter:blur(4px); user-select:none; pointer-events:none; white-space:pre-wrap; overflow-wrap:anywhere; }
.paid-note { color:var(--muted); font-size:15px; }
.candidate-grid,.paper-grid { display:grid; grid-template-columns:repeat(2,minmax(0,1fr)); gap:22px; }
.candidate-grid>div { border:1px solid var(--line); border-radius:10px; padding:16px; }
.boundary h3 { font-size:17px; }
.hero { padding:38px 28px; }
.hero h1 { font-size:clamp(28px,5vw,46px); }
.paper-link { display:block; border:1px solid var(--line); border-radius:10px; padding:22px; text-decoration:none; }
.paper-link strong { display:block; font-size:22px; }
.faq details { padding:12px 0; border-bottom:1px solid var(--line); }
.faq summary { cursor:pointer; font-weight:650; }
.page-note { border-left:4px solid var(--accent); padding:12px 16px; background:var(--bg); }
@media(max-width:650px) { .candidate-grid,.paper-grid { grid-template-columns:1fr; } .hero { padding:24px 18px; } }