.lesson { padding-top: clamp(28px, 5vw, 75px); }
.lesson-tabs { display: flex; flex-wrap: wrap; gap: 10px; padding-bottom: 20px; border-bottom: 1px solid var(--edge); }
.lesson-tabs a, .demo-buttons button { border: 1px solid var(--edge); background: #192128; color: var(--muted); padding: 9px 13px; font-size: .79rem; }
.lesson-tabs a span { color: var(--gold); margin-right: 4px; }
.lesson-tabs a:hover, .lesson-tabs a[aria-current], .demo-buttons button:hover { border-color: var(--gold); color: var(--ivory); }
.lesson-intro { margin: clamp(27px, 5vw, 72px) 0 34px; }
.lesson-intro p:not(.overline) { max-width: 62ch; color: var(--muted); }
.lesson-demo { display: grid; grid-template-columns: minmax(0, 1.8fr) minmax(260px, 1fr); border: 1px solid var(--edge); }
.diagram-plate { display: flex; flex-direction: column; justify-content: center; background: radial-gradient(ellipse at 50% 42%, #22313a, #10161d 73%); padding: clamp(13px, 2.7vw, 31px); }
.diagram-plate canvas { display: block; width: 100%; height: auto; margin: 4px 0 0; }
.demo-control { padding: clamp(16px, 3.5vw, 40px); background: var(--panel); }
.demo-control p:not(.overline), .lesson-pair p:not(.overline), .lesson-films p:not(.overline) { color: var(--muted); }
.axis-label { display: flex; justify-content: space-between; margin: 22px 0 7px; font-size: .8rem; }
.axis-label output { color: var(--gold); }
.demo-control input { width: 100%; height: 28px; accent-color: var(--gold); }
.demo-buttons { display: flex; flex-wrap: wrap; gap: 7px; margin: 10px 0 16px; }
.demo-buttons button { cursor: pointer; }
.demo-control p.diagram-status { color: var(--gold); font-size: .82rem; }
.lesson-pair { display: grid; grid-template-columns: repeat(2,minmax(0,1fr)); gap: 30px; padding-block: 46px 32px; }
.lesson-pair > * { border-top: 1px solid var(--edge); padding: 20px 0; }
.lesson-pair .film-poster { margin: 14px 0 0; max-width: 470px; }
.lesson-pair p a { color: var(--gold); text-decoration: underline; text-underline-offset: .2em; }
.lesson kbd { background: #252e36; border: 1px solid var(--edge); padding: 1px 5px; color: var(--ivory); border-radius: 3px; }
.lesson-films { display: grid; gap: 26px; }
.lesson-films article { display: grid; grid-template-columns: minmax(0,1fr) minmax(0,1fr); gap: clamp(17px,5vw,68px); align-items: center; padding: 22px 0; border-top: 1px solid var(--edge); }
.lesson-films .film-poster { margin: 0; }
.primer-hero { position: relative; isolation: isolate; }
.primer-hero img { position: absolute; z-index: -1; right: 0; top: 50%; transform: translateY(-50%); width: min(32%, 300px); height: auto; opacity: .82; }
.primer-index { display: flex; flex-wrap: wrap; gap: 6px 18px; padding: 13px 0; border-block: 1px solid var(--edge); }
.primer-index a { padding: 7px 0; color: var(--ivory); font-size: .83rem; }
.primer-index a:hover, .primer-index span { color: var(--gold); }
.primer-index span { margin-inline-end: 5px; }
.primer-chapter { margin-top: clamp(47px, 8vw, 104px); padding-top: clamp(22px, 4vw, 44px); border-top: 1px solid var(--edge); }
.primer-copy { max-width: 67ch; margin-bottom: 24px; }
.primer-copy p:not(.overline), .primer-questions p { color: var(--muted); line-height: 1.65; }
.primer-copy p + p { margin-top: 12px; }
.axis-cards { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 8px; margin: 0; }
.axis-cards div { padding: clamp(13px, 3vw, 32px); border: 1px solid var(--edge); background: #1b252d; }
.axis-cards div:last-child { background: #3c3146; border-color: #e9c38280; }
.axis-cards dt { color: var(--gold); font: 400 clamp(2rem, 5vw, 4.6rem)/1 var(--serif); }
.axis-cards dd { color: var(--ivory); margin: 8px 0 0; font-size: .87rem; }
.primer-note { max-width: 72ch; margin: 24px 0 0; padding: 12px 17px; border-inline-start: 2px solid var(--gold); background: #e9c38210; color: var(--muted); }
.primer-note strong { color: var(--ivory); }
.slice-analogy { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; padding: clamp(12px, 3.5vw, 42px); color: #342739; background: radial-gradient(ellipse at 0 0, #f4e7d5, transparent 80%), #d8cbd6; }
.slice-analogy > div { text-align: center; }
.slice-analogy svg { width: min(100%, 220px); height: auto; }
.slice-analogy strong, .slice-analogy span { display: block; }
.slice-analogy span, .slice-analogy figcaption { color: #554757; font-size: .84rem; }
.slice-analogy figcaption { grid-column: 1/-1; border-top: 1px solid #5f496847; padding-top: 12px; }
.primer-questions { display: grid; gap: 8px; max-width: 67ch; margin: 18px 0 27px; }
.primer-questions details { background: #212932; border: 1px solid var(--edge); padding: 13px 16px; }
.primer-questions summary { cursor: pointer; color: var(--ivory); }
.primer-questions p { margin-top: 8px; }
@media (max-width: 710px) {
  .lesson-demo, .lesson-pair, .lesson-films article { grid-template-columns: minmax(0,1fr); }
  .lesson-pair { gap: 12px; }
  .primer-hero img { width: 48%; opacity: .47; }
  .axis-cards { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 460px) {
  .slice-analogy { grid-template-columns: minmax(0, 1fr); gap: 12px; }
  .slice-analogy > div { display: grid; grid-template-columns: minmax(0, .8fr) minmax(0, 1fr); align-items: center; text-align: left; }
}