/* AI-103 practice exam — Notion-style: flat, warm neutrals, one blue accent. */
:root {
  --bg: #ffffff;
  --bg-2: #f7f6f3;
  --hover: #f1f1ef;
  --active: #e8e8e6;
  --text: #37352f;
  --muted: #787774;
  --border: #e9e9e7;
  --accent: #2383e2;
  --accent-text: #ffffff;
  --ok: #448361;
  --ok-bg: #edf3ec;
  --bad: #d44c47;
  --bad-bg: #fdebec;
  --warn: #cb912f;
  --warn-bg: #fbf3db;
  --zh: #5c5a55;
  --zh-bg: #f7f6f3;
  --radius: 6px;
  --sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial, sans-serif;
  --mono: "SF Mono", Menlo, Consolas, monospace;
  color-scheme: light;
}
:root[data-theme="dark"] {
  --bg: #191919;
  --bg-2: #202020;
  --hover: #2a2a2a;
  --active: #323232;
  --text: #e3e2e0;
  --muted: #9b9a97;
  --border: #2f2f2f;
  --accent: #529cca;
  --accent-text: #0f1b24;
  --ok: #4dab9a;
  --ok-bg: #1f3329;
  --bad: #e06c69;
  --bad-bg: #3a2222;
  --warn: #d9a441;
  --warn-bg: #3b2d14;
  --zh: #b9b7b3;
  --zh-bg: #232323;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html, body { margin: 0; }
body { background: var(--bg); color: var(--text); font: 15px/1.65 var(--sans); }
.mono { font-family: var(--mono); font-variant-numeric: tabular-nums; }
.muted { color: var(--muted); }
[hidden] { display: none !important; }
a { color: var(--accent); }

/* Compact single-row header */
.bar { position: sticky; top: 0; z-index: 5; display: flex; align-items: center; gap: 16px; padding: 8px 20px; background: var(--bg); border-bottom: 1px solid var(--border); flex-wrap: wrap; }
.brand { display: flex; align-items: baseline; gap: 10px; min-width: 0; }
.brand strong { font-size: 1.05rem; font-weight: 600; white-space: nowrap; }
.brand .sub { color: var(--muted); font-size: 13px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.bar-mid { display: flex; align-items: center; gap: 12px; margin-left: auto; }
.bar-actions { display: flex; gap: 6px; }
.bar-mid + .bar-actions { margin-left: 0; }
.brand + .bar-mid[hidden] + .bar-actions { margin-left: auto; }
.tag { font-size: 12px; padding: 2px 8px; border-radius: 4px; background: var(--bg-2); border: 1px solid var(--border); color: var(--muted); }
.timer { font-size: 1.05rem; font-weight: 600; padding: 2px 10px; border-radius: 4px; background: var(--bg-2); border: 1px solid var(--border); }
.timer.warn { color: var(--bad); background: var(--bad-bg); border-color: transparent; }

/* Buttons: background-only hover feedback, no movement */
.btn { font: inherit; font-size: 14px; color: var(--text); background: var(--bg); border: 1px solid var(--border); border-radius: var(--radius); padding: 6px 14px; cursor: pointer; transition: background .1s; }
.btn:hover:not(:disabled) { background: var(--hover); }
.btn:active:not(:disabled) { background: var(--active); }
.btn:disabled { opacity: .45; cursor: not-allowed; }
.btn.ghost { border-color: transparent; color: var(--muted); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-text); }
.btn.primary:hover:not(:disabled) { background: var(--accent); filter: brightness(.94); }
.btn[aria-pressed="true"] { background: var(--active); color: var(--text); }

main { max-width: 1180px; margin: 0 auto; padding: 20px; }
.card { background: var(--bg); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px 24px; }
h2 { font-size: 1.2rem; font-weight: 600; margin: 0; }
h3 { font-size: 1rem; font-weight: 600; margin: 16px 0 6px; }

/* Start screen */
.start { max-width: 720px; margin: 0 auto; display: grid; gap: 16px; }
.choice-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 10px; margin-top: 10px; }
.choice { display: flex; gap: 10px; padding: 12px 14px; border: 1px solid var(--border); border-radius: var(--radius); cursor: pointer; transition: background .1s; }
.choice:hover { background: var(--hover); }
.choice:has(input:checked) { border-color: var(--accent); background: var(--bg-2); }
.choice small { display: block; color: var(--muted); }
.check-row { display: flex; flex-direction: column; gap: 6px; margin-top: 8px; }
.check-row label { display: flex; gap: 8px; align-items: center; }
.resume { border-color: var(--accent); }
.actions { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 14px; }

/* Exam layout */
.exam-layout { display: grid; grid-template-columns: minmax(0, 1fr) 248px; gap: 20px; align-items: start; }
.q-head { display: flex; justify-content: space-between; align-items: center; gap: 12px; margin-bottom: 4px; }
.mark { display: flex; gap: 6px; align-items: center; color: var(--muted); font-size: 14px; cursor: pointer; }
.type-hint { font-size: 13px; color: var(--muted); margin-bottom: 8px; }
.prose p { margin: 0 0 10px; }
.stem { font-size: 15.5px; }

/* English / Chinese side by side (展开中文) */
.zh-split main { max-width: 1680px; }
.bilingual { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 24px; }
.pane { min-width: 0; }
.bilingual .pane-zh { border-left: 1px solid var(--border); padding-left: 24px; }
.pane-tag { font-size: 12px; padding: 0 8px; border-radius: 4px; background: var(--zh-bg); border: 1px solid var(--border); }
.bilingual .dragdrop, .bilingual .slot-row { grid-template-columns: 1fr; gap: 10px; }

.options { display: grid; gap: 8px; margin: 14px 0; }
.option { position: relative; display: flex; gap: 10px; align-items: flex-start; padding: 10px 12px; border: 1px solid var(--border); border-radius: var(--radius); cursor: pointer; transition: background .1s; }
.option:hover { background: var(--hover); }
.option.is-chosen { border-color: var(--accent); background: var(--bg-2); }
.option.is-correct { border-color: var(--ok); background: var(--ok-bg); }
.option.is-wrong { border-color: var(--bad); background: var(--bad-bg); }
.option input { margin-top: 5px; }
.letter { font-weight: 600; min-width: 1.1em; }
.option-body { flex: 1; }
.badge { font-size: 12px; padding: 1px 8px; border-radius: 4px; white-space: nowrap; }
.badge.ok { color: var(--ok); border: 1px solid var(--ok); }

.answer-area { display: grid; gap: 12px; margin: 14px 0; }
.slot-row { display: grid; grid-template-columns: minmax(140px, 220px) minmax(0, 1fr); gap: 12px; align-items: start; }
.slot-label { font-weight: 500; padding-top: 6px; }
select { font: inherit; font-size: 14px; color: var(--text); background: var(--bg); border: 1px solid var(--border); border-radius: var(--radius); padding: 6px 8px; width: 100%; }
.dragdrop { display: grid; grid-template-columns: minmax(180px, 280px) minmax(0, 1fr); gap: 20px; margin: 14px 0; }
.pool { display: grid; gap: 8px; align-content: start; }
.pool-title { font-size: 13px; color: var(--muted); font-weight: 600; }
.chip, .slot { border: 1px solid var(--border); border-radius: var(--radius); padding: 8px 10px; background: var(--bg); transition: background .1s; }
.chip { display: grid; grid-template-columns: 14px minmax(0, 1fr); column-gap: 6px; cursor: grab; overflow-wrap: anywhere; }
.chip > .zh { grid-column: 2; }
.chip:hover { background: var(--hover); }
.chip .grip { color: var(--muted); opacity: 0; transition: opacity .1s; }
.chip:hover .grip, .chip.is-picked .grip { opacity: 1; }
.chip.is-picked { border-color: var(--accent); background: var(--bg-2); }
.slot { min-height: 40px; border-style: dashed; cursor: pointer; }
.slot.filled { border-style: solid; }
.slot:hover { background: var(--hover); }
.placeholder { color: var(--muted); }
.slot-key { font-size: 14px; margin-top: 6px; }
.slot-key.ok { color: var(--ok); }
.slot-key.bad { color: var(--bad); }

.solution { margin-top: 18px; padding: 14px 18px; border-radius: var(--radius); border: 1px solid var(--border); background: var(--bg-2); }
.verdict { font-weight: 600; }
.solution.ok .verdict { color: var(--ok); }
.solution.bad .verdict { color: var(--bad); }
.meta { font-size: 14px; }
.refs ul { margin: 6px 0 0; padding-left: 20px; font-size: 14px; }

.q-actions { display: flex; gap: 10px; justify-content: flex-end; margin-top: 18px; border-top: 1px solid var(--border); padding-top: 14px; flex-wrap: wrap; }
.q-actions .spacer { flex: 1; }

/* Question palette */
.palette { position: sticky; top: 64px; padding: 16px; }
.grid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 6px; margin: 10px 0; max-height: min(420px, calc(100vh - 300px)); overflow-y: auto; padding: 2px; }
.cell { font: 12px var(--mono); height: 32px; border: 1px solid var(--border); border-radius: 4px; background: var(--bg); color: var(--muted); cursor: pointer; position: relative; }
.cell:hover { background: var(--hover); }
.cell.answered { background: var(--bg-2); color: var(--text); font-weight: 600; }
.cell.ok { background: var(--ok-bg); color: var(--ok); border-color: transparent; }
.cell.bad { background: var(--bad-bg); color: var(--bad); border-color: transparent; }
.cell.current { outline: 2px solid var(--accent); outline-offset: -1px; }
.cell.marked::after { content: ""; position: absolute; top: 3px; right: 3px; width: 6px; height: 6px; border-radius: 50%; background: var(--warn); }
.legend { font-size: 12px; line-height: 1.9; }
.palette .btn { width: 100%; margin-top: 8px; }

/* Results */
.result-head { margin-bottom: 14px; }
.stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 10px; margin-bottom: 14px; }
.stat { border: 1px solid var(--border); border-radius: var(--radius); padding: 12px 14px; }
.stat-value { font-size: 1.3rem; font-weight: 600; }
.stat-name { color: var(--muted); font-size: 13px; }
.stat.ok .stat-value { color: var(--ok); }
.stat.bad .stat-value { color: var(--bad); }
.result-actions { display: flex; gap: 10px; margin-bottom: 10px; }
.result-list { display: grid; gap: 4px; margin-top: 10px; }
.result-row { display: grid; grid-template-columns: 34px 24px 44px minmax(0, 1fr) 18px; gap: 10px; align-items: center; text-align: left; font: inherit; font-size: 14px; color: var(--text); background: var(--bg); border: 1px solid var(--border); border-radius: var(--radius); padding: 8px 12px; cursor: pointer; transition: background .1s; }
.result-row:hover { background: var(--hover); }
.result-row .text { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.result-row .type, .result-row .num { color: var(--muted); }
.result-row .status { font-weight: 700; text-align: center; }
.result-row.ok .status { color: var(--ok); }
.result-row.bad .status { color: var(--bad); }
.result-row.part .status, .result-row .flag { color: var(--warn); }
.notice { background: var(--warn-bg); color: var(--warn); padding: 10px 14px; border-radius: var(--radius); margin-bottom: 14px; }

dialog { border: 1px solid var(--border); border-radius: var(--radius); background: var(--bg); color: var(--text); padding: 20px 24px; max-width: 420px; }
dialog::backdrop { background: rgba(15, 15, 15, .35); }

@media (max-width: 860px) {
  .exam-layout, .dragdrop, .slot-row, .bilingual { grid-template-columns: 1fr; }
  .palette { position: static; }
  main { padding: 16px; }
  .card { padding: 16px; }
  .bar { padding: 8px 16px; }
  .brand .sub { display: none; }
}

.type-hint { display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; }
.qid { font-size: 12px; color: var(--muted); }
.area-text { font: 13px/1.6 var(--mono); background: var(--bg-2); border: 1px solid var(--border); border-radius: var(--radius); padding: 12px 14px; white-space: pre-wrap; overflow-x: auto; margin: 0 0 6px; }
.blank { padding: 0 4px; border-radius: 3px; border: 1px dashed var(--accent); color: var(--accent); }
.blank.filled { border-style: solid; }
.source-row { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; }
.source-row select { width: auto; min-width: 220px; }
.pool.code .chip > span:not(.grip) { font: 12.5px/1.5 var(--mono); }
.ai-note { color: var(--warn); background: var(--warn-bg); padding: 6px 10px; border-radius: 4px; font-size: 13.5px; }

/* ─── Phone layout ─────────────────────────────────────────────────────────── */
.mobile-only { display: none; }
.btn { -webkit-tap-highlight-color: transparent; }
#zhToggle .ico { display: none; }
.palette-head { display: flex; justify-content: space-between; align-items: center; }
.bar .btn .ico { margin-right: 4px; }
#questionCard { scroll-margin-top: 64px; }
.sheet-backdrop { position: fixed; inset: 0; z-index: 19; background: rgba(15, 15, 15, .35); }

@media (max-width: 860px) {
  /* One-row header: short title, progress + timer, icon-only toggles. */
  .bar { flex-wrap: nowrap; gap: 8px; padding: 6px 12px; }
  .brand-long, #modeChip, .bar .btn .lbl { display: none; }
  .bar .btn .ico { margin-right: 0; }
  .bar .btn { padding: 6px 10px; min-width: 38px; min-height: 38px; }
  .bar-mid { gap: 8px; }
  .bar-mid #progressText { font-size: 13px; }
  .timer { font-size: .95rem; padding: 2px 8px; }

  main { padding: 12px; }
  .card { padding: 14px; }
  .q-head h2 { font-size: 1.05rem; }
  .option { padding: 12px; }
  /* iOS zooms into any focused control under 16px. */
  select { font-size: 16px; }
  .wide-mobile { width: 100%; padding: 10px 14px; }
  .check-row label { align-items: flex-start; }
  .check-row label input { margin-top: 6px; }
  .source-row select { min-width: 0; width: 100%; }

  /* Actions stay reachable at the bottom of the screen. */
  .mobile-only { display: inline-block; }
  .q-actions { position: sticky; bottom: 0; z-index: 4; margin: 18px -14px -14px; padding: 10px 12px calc(10px + env(safe-area-inset-bottom)); background: var(--bg); gap: 6px; flex-wrap: nowrap; border-radius: 0 0 var(--radius) var(--radius); }
  .q-actions .spacer { display: none; }
  .q-actions .btn { flex: 1 1 0; padding: 10px 4px; min-width: 0; white-space: nowrap; }

  /* Question numbers become a bottom sheet. */
  .palette { position: fixed; left: 0; right: 0; bottom: 0; top: auto; z-index: 20; border-radius: 12px 12px 0 0; padding: 14px 16px calc(14px + env(safe-area-inset-bottom)); transform: translateY(100%); visibility: hidden; transition: transform .2s ease, visibility .2s; box-shadow: 0 -6px 24px rgba(0, 0, 0, .15); }
  .palette.open { transform: none; visibility: visible; }
  .palette .grid { grid-template-columns: repeat(auto-fill, minmax(44px, 1fr)); max-height: 46vh; }
  .palette .cell { height: 40px; font-size: 13px; }
  .palette-head .btn { width: auto; margin: 0; }
  body.sheet-open { overflow: hidden; }

  /* Phones: the header toggle switches language outright, so the bilingual view shows Chinese only. */
  #zhToggle .ico { display: inline; }
  .bilingual .pane-en { display: none; }
  .bilingual .pane-zh { border-left: 0; padding-left: 0; }
}
@media (prefers-reduced-motion: reduce) { .palette { transition: none; } }