:root {
  --bg: #f5f3ef;
  --surface: #ffffff;
  --surface-2: #faf8f5;
  --text: #1d1b18;
  --muted: #6d675f;
  --line: #e6e0d8;
  --primary: #2448b8;
  --primary-weak: #e9eefc;
  --on-primary: #ffffff;
  --brand: #c8102e;
  --gold: #e8a400;
  --ok: #18794e;
  --ok-weak: #e6f5ec;
  --bad: #c62828;
  --bad-weak: #fdecec;
  --shadow: 0 1px 2px rgba(30, 25, 20, .05), 0 6px 20px rgba(30, 25, 20, .05);
  --radius: 14px;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #121316;
    --surface: #1b1d22;
    --surface-2: #202329;
    --text: #e9e6e1;
    --muted: #9b968e;
    --line: #2d3038;
    --primary: #86a2ff;
    --primary-weak: rgba(134, 162, 255, .14);
    --on-primary: #0e1530;
    --brand: #e5394f;
    --gold: #f2c14e;
    --ok: #4ccf8a;
    --ok-weak: rgba(76, 207, 138, .13);
    --bad: #ff7b7b;
    --bad-weak: rgba(255, 123, 123, .13);
    --shadow: 0 1px 2px rgba(0, 0, 0, .3);
    color-scheme: dark;
  }
}

:root[data-theme="dark"] {
  --bg: #121316;
  --surface: #1b1d22;
  --surface-2: #202329;
  --text: #e9e6e1;
  --muted: #9b968e;
  --line: #2d3038;
  --primary: #86a2ff;
  --primary-weak: rgba(134, 162, 255, .14);
  --on-primary: #0e1530;
  --brand: #e5394f;
  --gold: #f2c14e;
  --ok: #4ccf8a;
  --ok-weak: rgba(76, 207, 138, .13);
  --bad: #ff7b7b;
  --bad-weak: rgba(255, 123, 123, .13);
  --shadow: 0 1px 2px rgba(0, 0, 0, .3);
  color-scheme: dark;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.65 -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", "Source Han Sans SC", sans-serif;
  -webkit-tap-highlight-color: transparent;
}

a { color: var(--primary); text-decoration: none; }
button, input, select { font: inherit; color: inherit; }
button { cursor: pointer; }
svg { display: block; }

.wrap {
  max-width: 760px;
  margin: 0 auto;
  padding: 0 16px calc(96px + env(safe-area-inset-bottom));
}

/* ---------- top bar ---------- */
.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: 760px;
  margin: 0 auto;
  padding: 10px 16px;
  background: var(--bg);
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(1.4) blur(10px);
  -webkit-backdrop-filter: saturate(1.4) blur(10px);
}
.brand { display: flex; align-items: center; gap: 10px; color: var(--text); font-weight: 700; font-size: 18px; letter-spacing: .02em; }
.brand-mark {
  width: 28px; height: 28px; border-radius: 8px; background: var(--brand);
  -webkit-mask: none;
  position: relative;
}
.brand-mark::after {
  content: ""; position: absolute; inset: 5px; background: #ffd54a;
  clip-path: polygon(50% 0, 61% 35%, 98% 35%, 68% 57%, 79% 91%, 50% 70%, 21% 91%, 32% 57%, 2% 35%, 39% 35%);
}
.topnav { display: flex; gap: 4px; }
.icon-btn {
  display: inline-grid; place-items: center;
  width: 40px; height: 40px; border-radius: 10px;
  border: 0; background: transparent; color: var(--muted);
}
.icon-btn:hover { background: var(--surface); color: var(--text); }
.icon-btn svg { width: 22px; height: 22px; }

/* ---------- generic ---------- */
h1, h2, h3 { line-height: 1.35; margin: 0; }
.muted { color: var(--muted); }
.section-title { font-size: 15px; color: var(--muted); font-weight: 600; margin: 28px 2px 10px; }

.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  min-height: 44px; padding: 0 18px;
  border-radius: 12px; border: 1px solid var(--line);
  background: var(--surface); color: var(--text); font-weight: 600;
  white-space: nowrap;
}
.btn:hover { border-color: var(--muted); }
.btn.primary { background: var(--primary); border-color: var(--primary); color: var(--on-primary); }
.btn.primary:hover { filter: brightness(1.07); }
.btn.danger { color: var(--bad); }
.btn:disabled { opacity: .45; cursor: not-allowed; filter: none; }
.btn svg { width: 18px; height: 18px; }
.btn-row { display: flex; flex-wrap: wrap; gap: 10px; }

.chip {
  display: inline-flex; align-items: center; min-height: 34px; padding: 0 14px;
  border-radius: 999px; border: 1px solid var(--line); background: var(--surface-2);
  color: var(--text); font-size: 14px; font-weight: 600;
}
.chip:hover { border-color: var(--primary); color: var(--primary); }

.tag {
  display: inline-block; padding: 1px 9px; border-radius: 6px;
  font-size: 13px; font-weight: 600;
  background: var(--primary-weak); color: var(--primary);
}
.tag.multi { background: rgba(200, 16, 46, .1); color: var(--brand); }
.tag.judge { background: rgba(232, 164, 0, .14); color: #a66f00; }
:root[data-theme="dark"] .tag.judge { color: var(--gold); }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .tag.judge { color: var(--gold); } }

.bar { height: 6px; border-radius: 99px; background: var(--line); overflow: hidden; }
.bar > i { display: block; height: 100%; background: var(--primary); border-radius: inherit; }

/* ---------- home ---------- */
.hero { padding: 18px 2px 4px; }
.hero h1 { font-size: 26px; letter-spacing: .02em; }
.hero p { margin: 6px 0 0; }

.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px; margin-top: 18px; }
.stat { padding: 14px 12px; text-align: center; }
.stat b { display: block; font-size: 22px; font-variant-numeric: tabular-nums; }
.stat span { font-size: 13px; color: var(--muted); }

.type-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; }
.type-card { display: flex; flex-direction: column; gap: 10px; padding: 16px; color: var(--text); }
.type-card:hover { border-color: var(--primary); }
.type-card h3 { font-size: 18px; }
.type-card .meta { display: flex; justify-content: space-between; font-size: 13px; color: var(--muted); }
.type-card .go { font-size: 14px; font-weight: 600; color: var(--primary); }

.mode-list { display: grid; gap: 10px; }
.mode { display: flex; align-items: center; gap: 14px; padding: 14px 16px; color: var(--text); }
a.mode:hover { border-color: var(--primary); }
.mode-icon {
  flex: none; display: grid; place-items: center;
  width: 44px; height: 44px; border-radius: 12px;
  background: var(--primary-weak); color: var(--primary);
}
.mode-icon svg { width: 22px; height: 22px; }
.mode-icon.red { background: rgba(200, 16, 46, .1); color: var(--brand); }
.mode-icon.gold { background: rgba(232, 164, 0, .15); color: var(--gold); }
.mode-icon.green { background: var(--ok-weak); color: var(--ok); }
.mode-body { flex: 1; min-width: 0; }
.mode-body h3 { font-size: 16px; }
.mode-body p { margin: 2px 0 0; font-size: 13px; color: var(--muted); }
.mode-chips { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 8px; }
.mode .count { font-weight: 700; font-variant-numeric: tabular-nums; color: var(--muted); }
.mode .chev { color: var(--muted); }
.mode .chev svg { width: 18px; height: 18px; }

.history { padding: 4px 16px; }
.history-row { display: flex; justify-content: space-between; align-items: center; padding: 10px 0; border-top: 1px solid var(--line); font-size: 14px; }
.history-row:first-child { border-top: 0; }
.history-row b { font-size: 16px; font-variant-numeric: tabular-nums; }

/* ---------- session ---------- */
.session-head {
  display: flex; align-items: center; gap: 8px;
  padding: 10px 0 12px;
}
.session-head .back { display: inline-flex; align-items: center; color: var(--muted); font-size: 15px; padding: 6px 6px 6px 0; }
.session-head .back svg { width: 20px; height: 20px; }
.session-head h1 { flex: 1; min-width: 0; font-size: 16px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.timer {
  font-variant-numeric: tabular-nums; font-weight: 700; font-size: 15px;
  padding: 4px 10px; border-radius: 8px; background: var(--surface); border: 1px solid var(--line);
}
.timer.low { color: var(--bad); border-color: var(--bad); }

.progress-line { height: 4px; border-radius: 9px; background: var(--line); overflow: hidden; margin-bottom: 14px; }
.progress-line > i { display: block; height: 100%; background: var(--primary); transition: width .25s ease; }

.qcard { padding: 20px 18px 18px; touch-action: pan-y; }
.qmeta { display: flex; align-items: center; gap: 8px; margin-bottom: 12px; font-size: 14px; }
.qmeta .qno { color: var(--muted); font-variant-numeric: tabular-nums; }
.qmeta .spacer { flex: 1; }
.star-btn {
  display: inline-flex; align-items: center; gap: 4px;
  border: 0; background: none; color: var(--muted); font-size: 14px; padding: 4px 2px;
}
.star-btn svg { width: 20px; height: 20px; }
.star-btn.on { color: var(--gold); }
.star-btn.on svg { fill: currentColor; }

.stem { font-size: 18px; font-weight: 600; line-height: 1.7; margin: 0 0 16px; word-break: break-word; }

.options { list-style: none; margin: 0; padding: 0; display: grid; gap: 10px; }
.opt {
  width: 100%; display: flex; align-items: flex-start; gap: 12px;
  padding: 12px 14px; text-align: left;
  border: 1.5px solid var(--line); border-radius: 12px; background: var(--surface-2);
  line-height: 1.6; transition: border-color .12s, background-color .12s;
}
.opt:hover:not(:disabled) { border-color: var(--primary); }
.opt:disabled { cursor: default; }
.opt .key {
  flex: none; display: grid; place-items: center;
  width: 28px; height: 28px; margin-top: -1px; border-radius: 50%;
  border: 1.5px solid var(--line); background: var(--surface);
  font-weight: 700; font-size: 14px; color: var(--muted);
}
.options.multi .opt .key { border-radius: 7px; }
.opt .txt { flex: 1; min-width: 0; word-break: break-word; }
.opt .mark { flex: none; width: 22px; height: 22px; margin-top: 2px; }
.opt.selected { border-color: var(--primary); background: var(--primary-weak); }
.opt.selected .key { background: var(--primary); border-color: var(--primary); color: var(--on-primary); }
.opt.correct { border-color: var(--ok); background: var(--ok-weak); }
.opt.correct .key { background: var(--ok); border-color: var(--ok); color: #fff; }
.opt.correct .mark { color: var(--ok); }
.opt.wrong { border-color: var(--bad); background: var(--bad-weak); }
.opt.wrong .key { background: var(--bad); border-color: var(--bad); color: #fff; }
.opt.wrong .mark { color: var(--bad); }
.opt.missed { border-style: dashed; }

.feedback { margin-top: 16px; padding: 12px 14px; border-radius: 12px; font-weight: 600; }
.feedback.ok { background: var(--ok-weak); color: var(--ok); }
.feedback.bad { background: var(--bad-weak); color: var(--bad); }
.feedback.info { background: var(--primary-weak); color: var(--primary); }
.feedback small { display: block; margin-top: 2px; font-weight: 400; color: var(--muted); }
.hint { margin-top: 12px; font-size: 13px; color: var(--muted); }

.action-bar {
  position: fixed; left: 0; right: 0; bottom: 0; z-index: 15;
  padding: 10px 16px calc(10px + env(safe-area-inset-bottom));
  background: var(--bg);
  background: color-mix(in srgb, var(--bg) 90%, transparent);
  backdrop-filter: saturate(1.4) blur(10px);
  -webkit-backdrop-filter: saturate(1.4) blur(10px);
  border-top: 1px solid var(--line);
}
.action-bar .inner { max-width: 728px; margin: 0 auto; display: grid; grid-template-columns: 1fr auto 1fr; gap: 10px; }
.action-bar .btn { width: 100%; }
.sheet-btn { min-width: 96px; font-variant-numeric: tabular-nums; }

/* ---------- answer sheet ---------- */
.overlay {
  position: fixed; inset: 0; z-index: 40;
  background: rgba(10, 10, 12, .45);
  display: flex; align-items: flex-end; justify-content: center;
  animation: fade .15s ease;
}
.sheet {
  width: 100%; max-width: 760px; max-height: 78vh; overflow: auto;
  background: var(--surface); border-radius: 18px 18px 0 0;
  padding: 18px 16px calc(18px + env(safe-area-inset-bottom));
  animation: rise .2s ease;
}
.sheet-head { display: flex; align-items: center; justify-content: space-between; margin-bottom: 8px; }
.sheet-head h2 { font-size: 17px; }
.legend { display: flex; flex-wrap: wrap; gap: 14px; font-size: 13px; color: var(--muted); margin-bottom: 6px; }
.legend i { display: inline-block; width: 12px; height: 12px; border-radius: 4px; margin-right: 5px; vertical-align: -1px; border: 1.5px solid var(--line); }
.legend i.ok { background: var(--ok); border-color: var(--ok); }
.legend i.bad { background: var(--bad); border-color: var(--bad); }
.legend i.filled { background: var(--primary); border-color: var(--primary); }
.sheet h3 { font-size: 14px; color: var(--muted); margin: 14px 0 8px; }
.cells { display: grid; grid-template-columns: repeat(auto-fill, minmax(42px, 1fr)); gap: 8px; }
.cell {
  height: 42px; border-radius: 10px; border: 1.5px solid var(--line);
  background: var(--surface-2); font-weight: 600; font-size: 14px; font-variant-numeric: tabular-nums;
}
.cell.ok { background: var(--ok); border-color: var(--ok); color: #fff; }
.cell.bad { background: var(--bad); border-color: var(--bad); color: #fff; }
.cell.filled { background: var(--primary); border-color: var(--primary); color: var(--on-primary); }
.cell.cur { outline: 2.5px solid var(--text); outline-offset: 2px; }

@keyframes fade { from { opacity: 0; } }
@keyframes rise { from { transform: translateY(24px); opacity: .6; } }

/* ---------- exam ---------- */
.form-card { padding: 6px 16px; }
.form-row { display: grid; grid-template-columns: 1fr auto auto; align-items: center; gap: 10px; padding: 12px 0; border-top: 1px solid var(--line); }
.form-row:first-child { border-top: 0; }
.form-row label { font-weight: 600; }
.form-row label small { display: block; font-weight: 400; color: var(--muted); font-size: 12px; }
.num {
  display: inline-flex; align-items: center; gap: 6px; font-size: 14px; color: var(--muted);
}
.num input {
  width: 64px; height: 38px; padding: 0 8px; text-align: center;
  border: 1px solid var(--line); border-radius: 9px; background: var(--surface-2);
  font-variant-numeric: tabular-nums;
}
.num input:focus, .search-box input:focus { outline: 2px solid var(--primary); outline-offset: 0; border-color: transparent; }
.total-line { display: flex; justify-content: space-between; margin: 14px 2px; font-weight: 600; }

.result { text-align: center; padding: 28px 16px 22px; }
.score-ring { --p: 0; position: relative; width: 168px; height: 168px; margin: 0 auto 14px; border-radius: 50%;
  background: conic-gradient(var(--ring, var(--primary)) calc(var(--p) * 1%), var(--line) 0); }
.score-ring::before { content: ""; position: absolute; inset: 12px; border-radius: 50%; background: var(--surface); }
.score-ring div { position: absolute; inset: 0; display: grid; place-content: center; }
.score-ring b { font-size: 46px; line-height: 1; font-variant-numeric: tabular-nums; }
.score-ring span { font-size: 13px; color: var(--muted); margin-top: 4px; }
.result .verdict { font-size: 18px; font-weight: 700; }
.result-table { width: 100%; border-collapse: collapse; margin-top: 16px; font-size: 14px; font-variant-numeric: tabular-nums; }
.result-table th, .result-table td { padding: 9px 6px; border-top: 1px solid var(--line); text-align: center; }
.result-table th { color: var(--muted); font-weight: 600; border-top: 0; }

/* ---------- search ---------- */
.search-box { position: relative; margin: 12px 0 8px; }
.search-box input {
  width: 100%; height: 48px; padding: 0 16px 0 44px;
  border: 1px solid var(--line); border-radius: 14px; background: var(--surface);
  font-size: 16px; box-shadow: var(--shadow);
}
.search-box svg { position: absolute; left: 14px; top: 14px; width: 20px; height: 20px; color: var(--muted); }
.results { display: grid; gap: 10px; margin-top: 10px; }
.result-item { display: block; width: 100%; text-align: left; padding: 14px 16px; color: var(--text); }
.result-item:hover { border-color: var(--primary); }
.result-item .stem-s { margin: 6px 0 4px; font-weight: 600; }
.result-item .ans { font-size: 14px; color: var(--ok); }
mark { background: rgba(232, 164, 0, .3); color: inherit; border-radius: 3px; padding: 0 1px; }

/* ---------- settings ---------- */
.set-list { padding: 2px 16px; }
.set-row { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 14px 0; border-top: 1px solid var(--line); }
.set-row:first-child { border-top: 0; }
.set-row p { margin: 0; }
.set-row small { display: block; color: var(--muted); font-size: 13px; }
.switch { position: relative; flex: none; width: 50px; height: 30px; border-radius: 99px; border: 0; background: var(--line); transition: background .15s; }
.switch::after { content: ""; position: absolute; top: 3px; left: 3px; width: 24px; height: 24px; border-radius: 50%; background: #fff; box-shadow: 0 1px 3px rgba(0,0,0,.25); transition: transform .15s; }
.switch[aria-checked="true"] { background: var(--primary); }
.switch[aria-checked="true"]::after { transform: translateX(20px); }
.seg { display: inline-flex; border: 1px solid var(--line); border-radius: 10px; overflow: hidden; }
.seg button { border: 0; background: transparent; padding: 6px 12px; font-size: 14px; }
.seg button[aria-pressed="true"] { background: var(--primary); color: var(--on-primary); }

.empty { text-align: center; padding: 48px 16px; }
.empty svg { width: 48px; height: 48px; margin: 0 auto 12px; color: var(--muted); }
.empty p { margin: 4px 0 18px; }

.toast {
  position: fixed; left: 50%; bottom: calc(92px + env(safe-area-inset-bottom)); z-index: 50;
  transform: translateX(-50%);
  padding: 9px 16px; border-radius: 10px; background: var(--text); color: var(--bg);
  font-size: 14px; box-shadow: var(--shadow); animation: fade .15s ease;
}

.foot { margin: 36px 0 0; text-align: center; font-size: 12px; color: var(--muted); }

@media (max-width: 560px) {
  .stats { grid-template-columns: repeat(2, 1fr); }
  .type-grid { grid-template-columns: 1fr; }
  .type-card { flex-direction: row; flex-wrap: wrap; align-items: center; }
  .type-card h3 { flex: 1; }
  .type-card .bar, .type-card .meta { flex-basis: 100%; }
  .stem { font-size: 17px; }
  .form-row { grid-template-columns: 1fr auto; }
  .form-row label { grid-column: 1 / -1; }
}

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
}