.lesson-head {
  padding-top: 62px;
  padding-bottom: 54px;
}
.back-link {
  display: inline-block;
  margin-bottom: 24px;
  font-size: 14px;
}
.lesson-head h1 {
  font-size: clamp(44px, 4.5vw, 64px);
  line-height: 1.12;
  margin-bottom: 24px;
}
.lesson-head > p {
  max-width: 68ch;
  margin-top: 16px;
  font-size: 19px;
}
.lesson-note,
.lesson-head > .lesson-note {
  font-size: 13px;
  line-height: 1.65;
  color: var(--ink-2);
}
.question-line {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 20px;
}
.question-line h2 {
  font-size: 27px;
}
.question-line > span {
  font-size: 13px;
  color: var(--ink-2);
}
.experiment {
  display: grid;
  grid-template-columns: 300px minmax(0, 1fr);
  border: 1px solid var(--line);
  background: var(--panel);
  border-radius: 10px;
  overflow: hidden;
}
.choices {
  background: var(--tint);
  border-right: 1px solid var(--line);
  padding: 28px;
}
.choices h3 {
  font-family: var(--sans);
  font-size: 16px;
  font-weight: 700;
  margin-bottom: 24px;
}
.choices label {
  display: block;
  font-weight: 600;
  font-size: 14px;
  margin-top: 22px;
  margin-bottom: 8px;
}
.choices select {
  width: 100%;
  min-height: 44px;
  padding: 10px 6px;
  border: 1px solid var(--line);
  border-radius: 5px;
  background: var(--panel);
  color: var(--ink);
  font: inherit;
  font-size: 13px;
}
.choices p {
  margin-top: 8px;
  color: var(--ink-2);
  font-size: 12px;
  line-height: 1.65;
}
.choices .btn {
  margin-top: 28px;
}
.evidence-view {
  padding: 30px 34px;
  min-height: 480px;
}
#result-status {
  font-size: 13px;
  color: var(--ink-2);
  margin-bottom: 18px;
}
.share-row {
  display: grid;
  grid-template-columns: 72px minmax(0, 1fr) 74px;
  align-items: center;
  gap: 15px;
  margin-bottom: 22px;
}
.share-row strong {
  text-align: right;
  font-size: 24px;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}
.share-track {
  height: 30px;
  position: relative;
  background: var(--rail);
  border-radius: 3px;
}
.share-fill {
  height: 100%;
  background: var(--accent);
  border-radius: 3px;
  transition: width 180ms ease-out;
}
.share-row:nth-child(2) .share-fill {
  background: var(--sage);
}
.share-interval {
  position: absolute;
  top: 13px;
  height: 4px;
  background: var(--ink);
  border-left: 2px solid var(--ink);
  border-right: 2px solid var(--ink);
}
.share-interval::before,
.share-interval::after {
  content: '';
  position: absolute;
  height: 12px;
  width: 2px;
  background: var(--ink);
  top: -4px;
}
.share-interval::before {
  left: -2px;
}
.share-interval::after {
  right: -2px;
}
.interval-caption {
  color: var(--ink-2);
  font-size: 12px;
}
.gap-line {
  display: flex;
  align-items: baseline;
  gap: 12px;
  border-top: 1px solid var(--line);
  padding-top: 20px;
  margin-top: 20px;
}
.gap-line strong {
  font-size: 32px;
  font-variant-numeric: tabular-nums;
}
.gap-line span,
.base-caption {
  font-size: 13px;
  color: var(--ink-2);
}
.base-caption {
  margin-top: 7px;
}
.people-title {
  font-family: var(--sans);
  font-size: 14px;
  font-weight: 600;
  margin-top: 30px;
}
.people-legend {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px;
  font-size: 11px;
  color: var(--ink-2);
  margin: 10px 0 14px;
}
.people-legend span {
  display: flex;
  align-items: center;
  gap: 5px;
}
.answer-dot {
  display: inline-block;
  border-radius: 50%;
  width: 8px;
  height: 8px;
}
.yes {
  background: var(--accent);
}
.no {
  background: var(--sage);
}
.missing {
  background: var(--line);
  border: 1px solid var(--ink-2);
}
.people-group {
  display: grid;
  grid-template-columns: 24px repeat(8, minmax(0, 1fr));
  gap: 6px;
  align-items: center;
  margin-bottom: 10px;
}
.person {
  padding: 8px 2px;
  border-bottom: 2px solid var(--line);
  text-align: center;
  font-size: 11px;
  line-height: 1.5;
}
.person strong {
  display: block;
  font-size: 13px;
}
.person.excluded {
  opacity: 0.48;
}
.person .answer-dot {
  display: block;
  margin: 5px auto;
}
.person-label {
  font-size: 9px;
}
.section-intro {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 50px;
  margin-bottom: 30px;
  align-items: end;
}
.section-intro h2 {
  font-size: 34px;
  line-height: 1.22;
}
.section-intro p {
  max-width: 55ch;
  color: var(--ink-2);
  font-size: 15px;
}
.uncertainty {
  padding-top: 72px;
}
.comparison {
  display: grid;
  grid-template-columns: 1fr 1fr;
  background: var(--panel);
  border-top: 3px solid var(--accent);
}
.method-result {
  padding: 26px 30px;
}
.method-result + .method-result {
  border-left: 1px solid var(--line);
}
.method-result h3 {
  font-family: var(--sans);
  font-size: 18px;
  font-weight: 600;
}
.method-result > p {
  font-size: 13px;
  color: var(--ink-2);
  margin-top: 9px;
}
.method-result dl {
  margin: 20px 0 0;
}
.method-result dl > div {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  padding: 9px 0;
  border-bottom: 1px solid var(--line-soft);
}
.method-result dt,
.method-result dd {
  font-size: 14px;
  margin: 0;
}
.method-result dd {
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}
.method-result .p-number {
  font-size: 32px;
}
.interpretation {
  margin: 22px 0 26px;
  max-width: 75ch;
}
.test-warning {
  padding: 16px 20px;
  margin-bottom: 18px;
  background: var(--accent-wash);
  border-left: 3px solid var(--accent);
  font-size: 14px;
}
.lesson details {
  border-top: 1px solid var(--line);
}
.lesson summary {
  padding: 19px 4px;
  font-weight: 600;
  font-size: 15px;
  cursor: pointer;
}
.detail-prose {
  padding: 0 4px 25px;
  max-width: 75ch;
}
.detail-prose p + p {
  margin-top: 16px;
}
.detail-prose p,
.arithmetic p {
  font-size: 14px;
}
.lesson code {
  font-family: ui-monospace, monospace;
  font-size: 0.9em;
  overflow-wrap: anywhere;
}
.mechanics {
  padding-top: 62px;
}
.arithmetic {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  padding: 5px 4px 28px;
}
.arithmetic h3 {
  font-family: var(--sans);
  font-size: 15px;
  margin-bottom: 10px;
  font-weight: 600;
}
.formula-line {
  font-size: 24px;
  font-weight: 600;
  margin-bottom: 10px;
  font-variant-numeric: tabular-nums;
}
#effective-math {
  margin: 18px 0;
  font-weight: 600;
}
.table-scroll {
  overflow-x: auto;
  padding-bottom: 24px;
}
.table-scroll table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  font-size: 13px;
}
.table-scroll caption {
  text-align: left;
  margin-bottom: 12px;
  color: var(--ink-2);
}
.table-scroll th,
.table-scroll td {
  padding: 9px 12px;
  border-bottom: 1px solid var(--line);
}
.table-scroll th {
  font-weight: 600;
  background: var(--rail);
}
.download-list {
  padding-left: 20px;
  margin: 18px 0;
}
.download-list li {
  margin-bottom: 9px;
  font-size: 14px;
}
.competitor-note {
  padding-top: 62px;
  padding-bottom: 80px;
}
.competitor-note h2 {
  font-size: 28px;
  margin-bottom: 18px;
}
.competitor-note p {
  max-width: 75ch;
  margin-top: 14px;
}
[hidden] {
  display: none !important;
}
.lesson [aria-disabled='true'] {
  opacity: 0.55;
  cursor: default;
}
@media (max-width: 1100px) {
  .experiment {
    grid-template-columns: 270px minmax(0, 1fr);
  }
  .choices {
    padding: 22px;
  }
  .evidence-view {
    padding: 26px;
  }
  .people-group {
    gap: 3px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .share-fill {
    transition: none;
  }
}