:root {
  --bg: #0f0f0f;
  --surface: #1a1a1a;
  --surface2: #242424;
  --border: #2e2e2e;
  --text: #e8e8e8;
  --muted: #888;
  --accent: #4f8ef7;
  --accent-dim: #1e3a6e;
  --correct: #22c55e;
  --correct-dim: #14532d;
  --wrong: #ef4444;
  --wrong-dim: #7f1d1d;
  --warn: #f59e0b;
  --radius: 8px;
  --mono: 'SF Mono', 'Fira Code', monospace;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { font-size: 15px; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  line-height: 1.6;
  min-height: 100vh;
}

/* ── Layout ── */
#app { max-width: 780px; margin: 0 auto; padding: 24px 16px 80px; }

/* ── Home ── */
#home { display: flex; flex-direction: column; gap: 24px; padding-top: 32px; }

.home-title {
  font-size: 1.6rem;
  font-weight: 700;
  letter-spacing: -0.5px;
}
.home-title span { color: var(--accent); }

.home-subtitle { color: var(--muted); font-size: 0.9rem; }

.mode-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(210px, 1fr)); gap: 12px; }

.mode-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  cursor: pointer;
  transition: border-color .15s, background .15s;
  text-align: left;
}
.mode-card:hover { border-color: var(--accent); background: var(--surface2); }

.mode-card h2 { font-size: 1rem; font-weight: 600; margin-bottom: 6px; }
.mode-card p { font-size: 0.82rem; color: var(--muted); line-height: 1.4; }
.mode-card .mode-icon { font-size: 1.5rem; margin-bottom: 10px; }

/* ── Config panels ── */
.config-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.config-panel h2 { font-size: 1.05rem; font-weight: 600; }

label { display: block; font-size: 0.85rem; color: var(--muted); margin-bottom: 6px; }

select, input[type=number] {
  width: 100%;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  padding: 9px 12px;
  font-size: 0.9rem;
  outline: none;
  appearance: none;
}
select:focus, input[type=number]:focus { border-color: var(--accent); }

.row { display: flex; gap: 12px; }
.row > * { flex: 1; }

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: var(--radius);
  padding: 10px 20px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: opacity .15s;
  width: 100%;
}
.btn:hover { opacity: .85; }
.btn.secondary {
  background: var(--surface2);
  color: var(--text);
  border: 1px solid var(--border);
}
.btn.danger { background: var(--wrong); }

/* ── Quiz header ── */
#quiz-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  padding: 10px 0;
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 24px;
}

.progress-bar-wrap {
  flex: 1;
  background: var(--surface2);
  border-radius: 99px;
  height: 6px;
  overflow: hidden;
}
.progress-bar-fill {
  height: 100%;
  background: var(--accent);
  border-radius: 99px;
  transition: width .3s;
}

.quiz-meta { font-size: 0.8rem; color: var(--muted); white-space: nowrap; }
.timer { font-size: 0.85rem; font-variant-numeric: tabular-nums; color: var(--text); }
.timer.warn { color: var(--warn); }
.timer.danger { color: var(--wrong); }

/* ── Question card ── */
.question-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 16px;
}

.q-meta {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 14px;
}

.tag {
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: .4px;
  text-transform: uppercase;
  padding: 3px 8px;
  border-radius: 4px;
  background: var(--surface2);
  color: var(--muted);
  border: 1px solid var(--border);
}
.tag.type-mc { border-color: #4f8ef755; color: var(--accent); }
.tag.type-ms { border-color: #8b5cf655; color: #8b5cf6; }
.tag.type-dd { border-color: #f59e0b55; color: var(--warn); }
.tag.type-hs { border-color: #22c55e55; color: var(--correct); }
.tag.type-sim { border-color: #ef444455; color: var(--wrong); }

.q-stem {
  font-size: 0.93rem;
  line-height: 1.65;
  white-space: pre-wrap;
  margin-bottom: 20px;
}

/* markdown-style tables in stem */
.q-stem table { border-collapse: collapse; font-size: 0.85rem; margin: 10px 0; width: 100%; }
.q-stem th, .q-stem td {
  border: 1px solid var(--border);
  padding: 6px 10px;
  text-align: left;
}
.q-stem th { background: var(--surface2); color: var(--muted); font-weight: 600; }

/* diagrams */
.diagrams { display: flex; flex-direction: column; gap: 10px; margin-bottom: 16px; }
/* diagrams injected between options or after them sit outside the .options flex container */
.options + .diagrams { margin-top: 10px; }
.diagram-item img {
  max-width: 100%;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  display: block;
}
.diagram-fallback {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius);
  padding: 12px 16px;
  font-size: 0.82rem;
  color: var(--muted);
  font-style: italic;
}
/* diagrams inside the feedback block */
.feedback .diagrams { margin-top: 12px; margin-bottom: 4px; }

/* options */
.options { display: flex; flex-direction: column; gap: 8px; }

.option {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 10px 14px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  cursor: pointer;
  transition: border-color .12s, background .12s;
  font-size: 0.88rem;
  line-height: 1.5;
}
.option-main { display: flex; align-items: flex-start; gap: 10px; }
.option-text { flex: 1; }
.option:hover:not(.disabled) { border-color: var(--accent); background: var(--surface2); }
.option.selected { border-color: var(--accent); background: var(--accent-dim); }
.option.correct { border-color: var(--correct); background: var(--correct-dim); }
.option.wrong { border-color: var(--wrong); background: var(--wrong-dim); }
.option.disabled { cursor: default; }

.option-key {
  font-weight: 700;
  font-size: 0.8rem;
  color: var(--muted);
  min-width: 18px;
  margin-top: 1px;
}
.option.selected .option-key { color: var(--accent); }
.option.correct .option-key { color: var(--correct); }
.option.wrong .option-key { color: var(--wrong); }

/* per-option rationale ("why this option is right / wrong") */
.option-rationale {
  padding-left: 28px;
  font-size: 0.82rem;
  line-height: 1.55;
}
.rationale-verdict {
  font-weight: 700;
  font-size: 0.78rem;
  letter-spacing: .2px;
  margin-bottom: 2px;
}
.rationale-verdict.good { color: var(--correct); }
.rationale-verdict.bad  { color: var(--wrong); }
.rationale-text { color: var(--muted); }
.option.correct .rationale-text,
.option.wrong .rationale-text { color: #cfcfcf; }

/* rationale under a hotspot Yes/No statement */
.row-rationale {
  margin-top: 6px;
  font-size: 0.8rem;
  color: var(--muted);
  line-height: 1.5;
}
.row-rationale .rationale-verdict { display: inline; margin-right: 4px; }

/* one-line "why this is the answer" summary at the top of the feedback block */
.answer-summary {
  margin-top: 10px;
  padding: 10px 12px;
  background: #ffffff08;
  border-radius: var(--radius);
  font-size: 0.86rem;
  line-height: 1.6;
  color: var(--text);
}
.answer-summary-label {
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: .6px;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 4px;
}

/* answer-review badge (verified / corrected / disputed) */
.verify-badge {
  margin-top: 10px;
  padding: 8px 12px;
  border-radius: var(--radius);
  border-left: 3px solid var(--muted);
  background: #ffffff08;
  font-size: 0.8rem;
}
.verify-badge .verify-head { font-weight: 700; letter-spacing: .2px; }
.verify-badge .verify-note { color: var(--muted); margin-top: 3px; line-height: 1.55; }
.verify-badge .verify-was { font-weight: 400; color: var(--muted); }
.verify-badge.ok { border-left-color: var(--correct); }
.verify-badge.ok .verify-head { color: var(--correct); }
.verify-badge.fixed { border-left-color: var(--accent); }
.verify-badge.fixed .verify-head { color: var(--accent); }
.verify-badge.disputed { border-left-color: var(--warn); }
.verify-badge.disputed .verify-head { color: var(--warn); }

/* hotspot yes/no table */
.hotspot-table { width: 100%; border-collapse: collapse; font-size: 0.88rem; }
.hotspot-table th {
  background: var(--surface2);
  color: var(--muted);
  padding: 8px 12px;
  text-align: left;
  border: 1px solid var(--border);
  font-weight: 600;
}
.hotspot-table td { border: 1px solid var(--border); padding: 8px 12px; vertical-align: middle; }
.hotspot-table tr:hover:not(.disabled) td { background: var(--surface2); }
.hotspot-table td.answer-cell { white-space: nowrap; }

.hs-btn {
  background: var(--surface2);
  border: 1px solid var(--border);
  color: var(--muted);
  border-radius: 4px;
  padding: 4px 12px;
  font-size: 0.8rem;
  cursor: pointer;
  margin-right: 4px;
  transition: all .12s;
}
.hs-btn.selected { border-color: var(--accent); background: var(--accent-dim); color: var(--accent); font-weight: 600; }
.hs-btn.correct { border-color: var(--correct); background: var(--correct-dim); color: var(--correct); font-weight: 600; }
.hs-btn.wrong { border-color: var(--wrong); background: var(--wrong-dim); color: var(--wrong); font-weight: 600; }
.hs-btn:disabled { cursor: default; }

/* drag-drop / dropdown */
.slots { display: flex; flex-direction: column; gap: 8px; }
.slot {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 10px 14px;
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  font-size: 0.88rem;
}
.slot-main { display: flex; align-items: center; gap: 10px; }
.slot-rationale { padding-left: 0; }
.slot-label { color: var(--muted); font-size: 0.82rem; min-width: 60px; }
.slot-answer {
  flex: 1;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
  padding: 6px 10px;
  font-size: 0.85rem;
  outline: none;
}
.slot-answer:focus { border-color: var(--accent); }
.slot.correct .slot-answer { border-color: var(--correct); background: var(--correct-dim); }
.slot.wrong .slot-answer { border-color: var(--wrong); background: var(--wrong-dim); }
.slot-correct-val {
  font-size: 0.8rem;
  color: var(--correct);
  font-weight: 600;
}

/* answer feedback */
.feedback {
  margin-top: 18px;
  padding: 14px 16px;
  border-radius: var(--radius);
  border-left: 3px solid var(--correct);
  background: var(--correct-dim);
  font-size: 0.85rem;
  line-height: 1.6;
  display: none;
}
.feedback.wrong-fb { border-color: var(--wrong); background: var(--wrong-dim); }
.feedback.show { display: block; }

.feedback-label {
  font-weight: 700;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: .5px;
  margin-bottom: 8px;
}
.feedback.wrong-fb .feedback-label { color: var(--wrong); }
.feedback:not(.wrong-fb) .feedback-label { color: var(--correct); }

.explanation-text {
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  white-space: pre-wrap;
  font-size: 0.83rem;
}

.community-votes {
  margin-top: 10px;
  font-size: 0.78rem;
  color: var(--muted);
}
.community-votes span { color: var(--text); }

/* AI Discussion panel */
.ai-discussion {
  margin-top: 14px;
  border: 1px solid #a78bfa55;
  border-left: 3px solid #a78bfa;
  border-radius: var(--radius);
  overflow: hidden;
}
.ai-discussion-toggle {
  width: 100%;
  text-align: left;
  background: #2a206044;
  border: none;
  padding: 8px 12px;
  cursor: pointer;
  font-size: 0.78rem;
  font-weight: 700;
  color: #a78bfa;
  letter-spacing: .3px;
  display: flex;
  align-items: center;
  gap: 6px;
}
.ai-discussion-toggle:hover { background: #2a206088; }
.ai-discussion-toggle .ai-chevron { transition: transform .2s; font-style: normal; }
.ai-discussion-toggle.open .ai-chevron { transform: rotate(90deg); }
.ai-discussion-body {
  display: none;
  padding: 10px 14px;
  font-size: 0.82rem;
  color: #c4b5fd;
  white-space: pre-wrap;
  line-height: 1.65;
  background: #1a1530;
}
.ai-discussion-body.open { display: block; }

/* nav buttons */
.q-actions {
  display: flex;
  gap: 10px;
  margin-top: 16px;
}
.q-actions .btn { width: auto; flex: 1; }

/* intro info */
.intro-toggle {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 10px 14px;
  font-size: 0.85rem;
  cursor: pointer;
  color: var(--accent);
  width: 100%;
  text-align: left;
  margin-bottom: 12px;
}
.intro-body {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  font-size: 0.83rem;
  color: var(--muted);
  white-space: pre-wrap;
  line-height: 1.6;
  margin-bottom: 16px;
  display: none;
}
.intro-body.open { display: block; }

/* ── Results ── */
#results { display: flex; flex-direction: column; gap: 20px; padding-top: 12px; }

.score-ring {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 32px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}
.score-number { font-size: 3.5rem; font-weight: 800; }
.score-number.pass { color: var(--correct); }
.score-number.fail { color: var(--wrong); }
.score-label { color: var(--muted); font-size: 0.85rem; }

.score-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
}
.stat-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  text-align: center;
}
.stat-box .val { font-size: 1.6rem; font-weight: 700; }
.stat-box .lbl { font-size: 0.75rem; color: var(--muted); margin-top: 2px; }

.result-actions { display: flex; gap: 10px; }
.result-actions .btn { flex: 1; }

/* ── Skipped / review list ── */
.review-list { display: flex; flex-direction: column; gap: 6px; }
.review-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 12px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  font-size: 0.85rem;
  cursor: pointer;
}
.review-item:hover { border-color: var(--accent); }
.review-dot { width: 8px; height: 8px; border-radius: 50%; flex-shrink: 0; }
.review-dot.correct { background: var(--correct); }
.review-dot.wrong { background: var(--wrong); }
.review-dot.skipped { background: var(--muted); }

/* ── Misc ── */
.hidden { display: none !important; }

.back-btn {
  background: none;
  border: none;
  color: var(--muted);
  cursor: pointer;
  font-size: 0.85rem;
  padding: 0;
  display: flex;
  align-items: center;
  gap: 4px;
}
.back-btn:hover { color: var(--text); }

hr { border: none; border-top: 1px solid var(--border); }

/* Scrollbar */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--bg); }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }

@media (max-width: 500px) {
  .score-stats { grid-template-columns: 1fr 1fr; }
  .row { flex-direction: column; }
}