:root {
  --bg: #faf5ff;
  --surface: #fff;
  --text: #0f172a;
  --muted: #475569;
  --border: #e9ddfb;
  --primary: #6d28d9;
  --primary-hover: #5b21b6;
  --soft: #f3e8ff;
  --answer: #047857;
  --answer-bg: #ecfdf5;
  --wrong: #b91c1c;
  --wrong-bg: #fef2f2;
  --warning: #9a3412;
  --warning-bg: #fff7ed;
  --warning-border: #fdba74;
  --ring: #7c3aed;
  --on-primary: #fff;
  --surface-soft: #faf7ff;
  --surface-hover: #f6f0ff;
  --border-strong: #c4b5fd;
  --domain-bg: #ede9fe;
  --domain-text: #5b21b6;
  --topic-bg: #eef2ff;
  --topic-text: #3730a3;
  --topic-border: #a5b4fc;
  --pillar-bg: #f8fafc;
  --pillar-text: #475569;
  --pillar-border: #cbd5e1;
  --legacy-bg: #fffbeb;
  --legacy-text: #78350f;
  --legacy-strong-text: #92400e;
  --legacy-border: #f59e0b;
  --marked-bg: #fef3c7;
  --marked-text: #92400e;
  --marked-border: #d97706;
  --control-radius: 10px;
  --motion-fast: 160ms;
  --motion-standard: 220ms;
  --ease-out: cubic-bezier(.2, .8, .2, 1);
  --shadow: 0 12px 32px rgba(76, 29, 149, .08);
  --modal-shadow: 0 24px 64px rgba(38, 16, 75, .22);
  --modal-scrim: rgba(26, 16, 41, .68);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; background: var(--bg); color: var(--text); font: 16px/1.65 system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif; }
button, input { font: inherit; }
button { cursor: pointer; }
.skip { position: absolute; left: -999px; top: 8px; }
.skip:focus { left: 8px; z-index: 5; background: var(--surface); padding: 10px; border: 2px solid var(--ring); }
header { position: sticky; top: 0; z-index: 3; background: rgba(250, 245, 255, .96); border-bottom: 1px solid var(--border); backdrop-filter: blur(12px); }
.bar { max-width: 1180px; margin: auto; padding: 16px 20px; display: grid; grid-template-columns: 1fr minmax(240px, 420px); gap: 18px; align-items: center; }
h1 { font-size: clamp(1.2rem, 3vw, 1.7rem); margin: 0; }
.meta { margin: 2px 0 0; color: var(--muted); font-size: .9rem; }
.search-label { display: block; font-weight: 700; font-size: .85rem; }
#search { width: 100%; min-height: 46px; padding: 10px 14px; border: 1px solid #a78bfa; border-radius: 10px; background: var(--surface); color: var(--text); }
input:focus-visible, button:focus-visible, .option:focus-within { outline: 3px solid var(--ring); outline-offset: 2px; }
main { max-width: 850px; margin: 0 auto; padding: 28px 20px 80px; }
.notice { background: #fff7ed; border: 1px solid #fdba74; border-radius: 12px; padding: 14px 16px; margin-bottom: 24px; }
.count { color: var(--muted); margin: 0 0 18px; }
article { position: relative; background: var(--surface); border: 1px solid var(--border); border-radius: 16px; padding: clamp(18px, 4vw, 32px); margin: 0 0 20px; box-shadow: var(--shadow); }
h2 { font-size: 1rem; color: var(--primary); margin: 0 0 12px; }
.question-heading { position: relative; min-height: 44px; padding-right: 58px; margin: 0 0 12px; }
.question-heading h2 { margin: 0; }
.question-heading h2 small { margin-left: 5px; color: var(--muted); font-size: .72rem; font-weight: 650; }
.question-meta { display: flex; align-items: center; flex-wrap: wrap; gap: 5px; margin-top: 2px; color: var(--muted); font-size: .8rem; line-height: 1.4; }
.question-meta a { color: var(--primary); font-weight: 700; text-underline-offset: 3px; }
.question-meta a:hover { color: var(--primary-hover); }
.visually-hidden { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }
.copy-question { position: absolute; z-index: 1; top: clamp(18px, 4vw, 32px); right: clamp(18px, 4vw, 32px); display: inline-flex; align-items: center; justify-content: center; gap: 7px; min-height: 44px; padding: 8px 12px; border: 1px solid #a78bfa; border-radius: 10px; background: var(--surface); color: var(--primary); font-size: .875rem; font-weight: 750; line-height: 1; transition: background-color .18s, border-color .18s, color .18s; }
.copy-question:hover { border-color: var(--primary); background: var(--soft); }
.copy-question.copied { border-color: var(--answer); background: var(--answer-bg); color: var(--answer); }
.mark-question { position: absolute; top: 0; right: 0; display: grid; width: 44px; height: 44px; place-items: center; padding: 0; border: 0; border-radius: 8px; background: transparent; color: #64748b; transition: color .18s, background-color .18s; }
.mark-question .flag-fill { fill: transparent; transition: fill .18s; }
.mark-question:hover, .mark-question.active { background: var(--soft); color: var(--primary); }
.mark-question:hover .flag-fill, .mark-question.active .flag-fill { fill: currentColor; }
.prompt { margin: 0 0 20px; padding: 16px 18px; border-left: 4px solid #c4b5fd; border-radius: 0 10px 10px 0; background: #faf7ff; font-size: 1.025rem; line-height: 1.72; }
.prompt p { margin: 0; }
.prompt p + p { margin-top: 12px; padding-top: 12px; border-top: 1px solid var(--border); }
.prompt-list { margin: 12px 0; padding-left: 24px; }
.prompt-list li + li { margin-top: 8px; }
.question-media { margin: 16px 0; padding: 12px; border: 1px solid var(--border); border-radius: 10px; background: #fff; text-align: center; }
.question-media img { display: block; width: auto; max-width: 100%; height: auto; margin: 0 auto; }
.option > span { white-space: pre-line; }
.option-image { display: block; width: auto; max-width: 100%; height: auto; margin-top: 10px; border-radius: 6px; }
fieldset { border: 0; padding: 0; margin: 0; }
legend { font-size: .875rem; font-weight: 700; color: var(--muted); margin-bottom: 10px; }
.options { display: grid; gap: 10px; }
.option { display: grid; grid-template-columns: auto 1fr; gap: 12px; align-items: start; min-height: 52px; padding: 12px 14px; border: 1px solid var(--border); border-radius: 12px; cursor: pointer; transition: background-color .18s, border-color .18s, box-shadow .18s; }
.option:hover { border-color: #a78bfa; background: #faf7ff; }
.option.locked { cursor: default; }
.option.locked:not(.correct):not(.wrong):not(.missed):hover { border-color: var(--border); }
.option.locked input { cursor: not-allowed; }
.option input { width: 20px; height: 20px; margin: 3px 0 0; accent-color: var(--primary); }
.option.selected { border-color: var(--primary); background: var(--soft); box-shadow: 0 0 0 1px var(--primary); }
.option.correct { border-color: var(--answer); background: var(--answer-bg); box-shadow: inset 4px 0 var(--answer); }
.option.wrong { border-color: var(--wrong); background: var(--wrong-bg); box-shadow: inset 4px 0 var(--wrong); }
.option.missed { border-color: var(--answer); background: var(--answer-bg); border-style: dashed; }
.choice-label { font-weight: 800; color: var(--primary); margin-right: 6px; }
.actions { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; margin-top: 18px; }
.reveal { min-height: 46px; border: 0; border-radius: 10px; padding: 10px 18px; background: var(--primary); color: #fff; font-weight: 750; }
.reveal:hover { background: var(--primary-hover); }
.reveal:disabled { cursor: default; background: #64748b; }
.feedback { flex: 1; min-width: 220px; border-radius: 10px; padding: 11px 14px; font-weight: 700; }
.feedback.correct { color: #065f46; background: var(--answer-bg); }
.feedback.wrong { color: #991b1b; background: var(--wrong-bg); }
.feedback.neutral { color: #334155; background: #f1f5f9; }
.answer-key { display: block; font-weight: 500; margin-top: 2px; }
.empty { padding: 50px 0; text-align: center; color: var(--muted); }
.year-divider { display: flex; align-items: baseline; gap: 10px; margin: 28px 0 12px; color: var(--text); }
.year-divider:first-child { margin-top: 0; }
.year-divider span { font-size: 1.35rem; font-weight: 850; letter-spacing: -.02em; }
.year-divider small { color: var(--muted); font-size: .8rem; font-weight: 700; }
.case-divider { display: flex; align-items: center; gap: 10px; margin: 18px 0 10px; padding: 9px 13px; border: 1px solid #d8c7f5; border-radius: 10px; background: var(--soft); color: var(--primary); }
.case-divider span { font-size: .9rem; font-weight: 850; }
.case-divider small { color: var(--muted); font-size: .75rem; font-weight: 700; }
.case-divider b { margin-left: auto; padding: 3px 7px; border: 1px solid #a78bfa; border-radius: 999px; background: var(--surface); font-size: .65rem; letter-spacing: .04em; text-transform: uppercase; }
.case-divider:not(.general)::before { content: "Case study"; padding: 3px 6px; border-radius: 5px; background: var(--primary); color: #fff; font-size: .62rem; font-weight: 850; letter-spacing: .06em; text-transform: uppercase; }
.case-divider.general { border-style: dashed; background: transparent; color: var(--muted); }
.case-group { display: flow-root; }
.case-context { position: sticky; top: var(--reader-sticky-offset, 128px); z-index: 4; margin: 18px 0 14px; border: 1px solid #d8c7f5; border-radius: 12px; background: var(--surface); box-shadow: 0 8px 24px rgba(76,29,149,.12); overflow: hidden; }
.case-context summary { min-height: 48px; display: flex; align-items: center; gap: 10px; padding: 9px 13px; color: var(--primary); font-size: .85rem; font-weight: 800; cursor: pointer; list-style: none; }
.case-context summary::-webkit-details-marker { display: none; }
.case-context summary::before { content: "Case study"; padding: 3px 6px; border-radius: 5px; background: var(--primary); color: #fff; font-size: .62rem; font-weight: 850; letter-spacing: .06em; text-transform: uppercase; }
.case-context summary .context-name { font-size: .9rem; font-weight: 850; }
.case-context summary small { color: var(--muted); font-size: .75rem; font-weight: 700; }
.case-context summary b { padding: 3px 7px; border: 1px solid #a78bfa; border-radius: 999px; background: var(--surface); font-size: .65rem; letter-spacing: .04em; text-transform: uppercase; }
.case-context summary:hover { background: var(--soft); }
.case-context[open] summary { border-bottom: 1px solid var(--border); background: var(--soft); }
.case-context > div { max-width: 900px; padding: 18px; }
.case-context[open] > div { max-height: calc(100dvh - var(--reader-sticky-offset, 128px) - 62px); overflow-y: auto; overscroll-behavior: contain; }
.case-context section + section { margin-top: 22px; padding-top: 18px; border-top: 1px solid var(--border); }
.case-context h4 { margin: 0 0 8px; color: var(--primary); font-size: .82rem; letter-spacing: .04em; text-transform: uppercase; }
.case-context p { margin: 0; color: var(--text); line-height: 1.7; }
.case-context p + p { margin-top: 10px; }
.case-context ul { margin: 8px 0 0; padding-left: 20px; }
.case-context li { margin: 6px 0; line-height: 1.6; }
.case-context h5 { margin: 14px 0 5px; font-size: .85rem; }
.case-context .context-group { padding-left: 12px; border-left: 2px solid var(--border); }
.case-context .context-source { margin-top: 24px; padding: 12px 14px; border-radius: 8px; background: #f1f5f9; color: var(--muted); font-size: .78rem; }
.context-source a { color: var(--primary); font-weight: 700; }

@media (max-width: 700px) {
  .bar { grid-template-columns: 1fr; }
  header { position: static; }
  main { padding-inline: 14px; }
  article { border-radius: 12px; }
  .question-heading { padding-right: 52px; }
  .copy-question span { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }
  .copy-question { min-width: 44px; padding-inline: 12px; }
  .reveal { width: 100%; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .option { transition: none; }
}