:root {
  --bg: #ffffff;
  --fg: #16181d;
  --muted: #5b6270;
  --line: #d9dde5;
  --accent: #0b5fff;
  --answer-bg: #eef4ff;
  --answer-fg: #073ea8;
  --correct: #1a7f37;
  --correct-bg: #eaf7ee;
  --incorrect: #c4341f;
  --incorrect-bg: #fbeceb;
  --radius: 10px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #101216;
    --fg: #f2f4f8;
    --muted: #9aa3b2;
    --line: #2a2f39;
    --accent: #6aa1ff;
    --answer-bg: #17233d;
    --answer-fg: #bcd4ff;
    --correct: #4fd57a;
    --correct-bg: #122a1a;
    --incorrect: #ff8a7a;
    --incorrect-bg: #2e1512;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  padding: 0 1rem 3rem;
  background: var(--bg);
  color: var(--fg);
  font: 400 17px/1.5 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  -webkit-text-size-adjust: 100%;
}

.masthead {
  max-width: 46rem;
  margin: 0 auto;
  padding: 1.5rem 0 1rem;
  border-bottom: 1px solid var(--line);
}

h1 {
  margin: 0;
  font-size: 1.5rem;
  letter-spacing: -0.01em;
}

.date {
  margin: 0.25rem 0 0;
  color: var(--muted);
  font-size: 1rem;
}

.notice {
  margin: 0.75rem 0 0;
  padding: 0.5rem 0.75rem;
  border-left: 3px solid var(--accent);
  background: var(--answer-bg);
  color: var(--answer-fg);
  font-size: 0.9rem;
  border-radius: 0 var(--radius) var(--radius) 0;
}

.controls {
  display: flex;
  gap: 0.5rem;
  align-items: center;
  margin-top: 1rem;
}

.tally {
  margin: 0.5rem 0 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0 1rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: transparent;
  color: var(--fg);
  font: inherit;
  text-decoration: none;
  cursor: pointer;
}

.btn:hover { border-color: var(--accent); }
.btn:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }

.btn-primary {
  flex: 1;
  border-color: var(--accent);
  background: var(--accent);
  color: #fff;
  font-weight: 600;
}

main { max-width: 46rem; margin: 0 auto; }

.questions {
  margin: 0;
  padding: 0 0 0 2.25rem;
  list-style: decimal;
}

.questions > li {
  border-bottom: 1px solid var(--line);
  padding: 0.25rem 0;
}

.questions > li.marked-correct {
  background: var(--correct-bg);
  border-left: 4px solid var(--correct);
  padding-left: 0.5rem;
}

.questions > li.marked-incorrect {
  background: var(--incorrect-bg);
  border-left: 4px solid var(--incorrect);
  padding-left: 0.5rem;
}

.questions > li::marker {
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

summary {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  /* 44px minimum keeps this a comfortable touch target in studio. */
  min-height: 44px;
  padding: 0.85rem 0;
  cursor: pointer;
  list-style: none;
}

summary::-webkit-details-marker { display: none; }
summary:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }

.question { font-weight: 600; }

.hint {
  color: var(--muted);
  font-size: 0.85rem;
}

details[open] .hint { display: none; }

.answer {
  margin: 0 0 0.9rem;
  padding: 0.65rem 0.85rem;
  border-radius: var(--radius);
  background: var(--answer-bg);
  color: var(--answer-fg);
  font-weight: 700;
}

.mark-controls {
  display: flex;
  gap: 0.5rem;
  margin: 0 0 0.9rem;
}

.mark-correct[aria-pressed="true"] {
  border-color: var(--correct);
  background: var(--correct);
  color: #fff;
}

.mark-incorrect[aria-pressed="true"] {
  border-color: var(--incorrect);
  background: var(--incorrect);
  color: #fff;
}

.swap-form {
  margin: 0.9rem 0 0.9rem;
  padding-top: 0.6rem;
  border-top: 1px dashed var(--line);
}

.swap {
  min-height: 40px;
  padding: 0 0.85rem;
  font-size: 0.85rem;
  color: var(--muted);
}

.page-footer {
  max-width: 46rem;
  margin: 2rem auto 0;
  padding-top: 1rem;
  border-top: 1px solid var(--line);
  display: flex;
  justify-content: space-between;
  font-size: 0.9rem;
}

.page-footer a { color: var(--accent); }
.muted { color: var(--muted); }

.print-list .question { margin: 0.85rem 0 0.35rem; }
.print-list .answer { display: inline-block; margin-bottom: 0.85rem; }

@media print {
  :root {
    --bg: #fff;
    --fg: #000;
    --muted: #444;
    --line: #bbb;
    --answer-bg: transparent;
    --answer-fg: #000;
  }
  body { font-size: 12pt; padding: 0; }
  .no-print, .controls, .page-footer, .hint, .tally, .mark-controls { display: none !important; }
  .questions > li { break-inside: avoid; }
  .answer { padding: 0; border: 0; }
  .answer::before { content: "Answer: "; font-weight: 400; }
  details > summary { list-style: none; }
  details:not([open]) > .answer { display: block; }
}