/* ---- the lesson as beats on the 12-column grid: every beat lands somewhere different ---- */
  .sec .g12 { row-gap: clamp(48px, 7vw, 120px); }
  .c1-5 { grid-column: 1 / 5; } .c1-6 { grid-column: 1 / 6; } .c1-7 { grid-column: 1 / 7; } .c1-8 { grid-column: 1 / 8; } .c1-12 { grid-column: 1 / 12; } .c1-13 { grid-column: 1 / 13; }
  .c2-13 { grid-column: 2 / 13; } .c5-9 { grid-column: 5 / 9; } .c5-13 { grid-column: 5 / 13; } .c6-13 { grid-column: 6 / 13; } .c7-12 { grid-column: 7 / 12; } .c7-13 { grid-column: 7 / 13; } .c8-13 { grid-column: 8 / 13; } .c9-13 { grid-column: 9 / 13; }
  .sec .g12 > .eyebrow { margin-bottom: calc(-1 * clamp(24px, 4vw, 72px)); }
  .beat { display: grid; align-content: center; gap: var(--sp-3); }
  .beat .big { margin: 0; font-size: var(--h4); font-weight: 500; line-height: 1.3; color: var(--text-heading); text-wrap: balance; }
  .beat .big.xl { font-size: var(--h3); line-height: 1.12; }
  .beat .big b { font-weight: 500; color: var(--link); }
  .beat .small { margin: 0; color: var(--text); font-size: var(--text-body); max-width: 46ch; }
  .beat .k { font-family: var(--f-03); font-size: var(--text-xs); letter-spacing: .14em; text-transform: uppercase; }
  .beat.end { align-self: end; text-align: right; }
  /* the big words: the word on one side, its copy on the other, and the second one flipped */
  .beat.word { grid-template-columns: repeat(12, 1fr); column-gap: var(--sp-5); align-items: end; }
  .beat.word .w { grid-column: 1 / 7; font-weight: 500; font-size: var(--h1); line-height: .95; letter-spacing: -.03em; }
  .beat.word .wt { grid-column: 7 / 13; display: grid; gap: var(--sp-3); }
  .beat.word.flip .w { grid-column: 7 / 13; grid-row: 1; text-align: right; }
  .beat.word.flip .wt { grid-column: 1 / 6; grid-row: 1; }
  /* the pace pair: the second one sits lower */
  .beat.pace { border-top: 2px solid var(--border-subtle); padding-top: var(--sp-4); gap: var(--sp-2); }
  .beat.pace.low { margin-top: clamp(64px, 10vw, 160px); }
  /* the ladder as a staircase */
  .stair { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(8, 1fr); row-gap: var(--sp-2); }
  .stair li { grid-column: span 5; display: grid; gap: 2px; padding: var(--sp-4); border: var(--border-w) solid var(--border-subtle); border-radius: var(--radius-main); background: var(--background-2); }
  .stair li:nth-child(2) { grid-column: 2 / 7; } .stair li:nth-child(3) { grid-column: 3 / 8; } .stair li:nth-child(4) { grid-column: 4 / 9; }
  .stair b { font-weight: 500; } .stair i { font-style: normal; color: var(--text); font-size: var(--text-s); }
  /* the three cards step down */
  .beat.mon { grid-template-columns: 1fr; grid-column: auto; margin-top: 0; border-top: 2px solid var(--border-subtle); padding-top: var(--sp-4); align-content: start; }
  .beat.mon.c1-5 { grid-column: 1 / 5; } .beat.mon.c5-9 { grid-column: 5 / 9; } .beat.mon.c9-13 { grid-column: 9 / 13; }
  .beat.mon > .icon { font-size: 36px; color: var(--link); }
  .beat.mon.step1 { margin-top: clamp(48px, 8vw, 120px); } .beat.mon.step2 { margin-top: clamp(96px, 16vw, 240px); }
  /* the promise and the recap */
  .promise { list-style: none; margin: 0; padding: 0; display: grid; align-self: center; }
  .promise li { display: grid; grid-template-columns: 56px 1fr; gap: 4px var(--sp-4); padding: var(--sp-4) 0; border-top: var(--border-w) solid var(--border-subtle); }
  .promise li:last-child { border-bottom: var(--border-w) solid var(--border-subtle); }
  .promise .n { grid-row: 1 / 3; font-family: var(--f-03); font-size: var(--h4); color: var(--link); line-height: 1; }
  .promise .t { color: var(--text-heading); font-weight: 500; font-size: var(--text-l); }
  .promise .s { color: var(--text); font-size: var(--text-s); }
  /* the slides sit off-centre, with the caption in the spare column */
  .slide { margin: 0; display: grid; gap: var(--sp-3); }
  .slide .sl { width: 100%; box-shadow: 0 40px 120px rgba(0, 0, 0, .5); border-radius: 12px; }
  .slide figcaption { margin: 0; display: flex; gap: var(--sp-3); align-items: baseline; color: var(--text); font-size: var(--text-s); }
  .slide figcaption .mono-xs { color: var(--link); }
  .slide.c1-12 figcaption { justify-content: flex-end; }
  .slide.reveal { transform: scale(.96) translateY(24px); opacity: .4; transition: transform .9s cubic-bezier(.2,.7,.2,1), opacity .9s ease; }
  .slide.reveal.in { transform: none; opacity: 1; }
  .slide .q { font-size: clamp(22px, 3vw, 46px); }
  .slide .two > div { font-size: clamp(15px, 1.8vw, 26px); }
  .slide .two b { font-size: clamp(26px, 3.4vw, 54px); }
  .slide .eq { font-size: clamp(18px, 2.8vw, 44px); }
  .slide .defs { font-size: clamp(15px, 1.8vw, 26px); gap: 10px; }
  .slide .bigs { font-size: clamp(20px, 3.2vw, 50px); text-wrap: balance; max-width: 22ch; margin-inline: auto; }
  .slide .sl { padding: clamp(24px, 5vw, 88px) clamp(24px, 6vw, 110px); gap: clamp(18px, 3vw, 44px); }
  /* a story: a sticky figure that fills in while the beats beside it scroll past; the second story swaps sides */
  .story { display: grid; grid-template-columns: 1fr 1fr; gap: var(--sp-8); align-items: start; }
  .story .stick { position: sticky; top: 24vh; }
  .story.swap .stick { grid-column: 2; grid-row: 1; } .story.swap .beats { grid-column: 1; grid-row: 1; }
  .story .beats .beat { min-height: 50vh; }
  .story .beat { opacity: .28; transition: opacity .5s ease; } .story .beat.on { opacity: 1; }
  .fx .t1, .fx .t2, .fx .t3, .fx .t4, .score .t1, .score .t2, .score .t3, .score .t4 { opacity: .16; transition: opacity .5s ease; }
  [data-step="1"] .t1, [data-step="2"] .t1, [data-step="2"] .t2, [data-step="3"] .t1, [data-step="3"] .t2, [data-step="3"] .t3, [data-step="4"] .t1, [data-step="4"] .t2, [data-step="4"] .t3, [data-step="4"] .t4 { opacity: 1; }
  .formula.fx { padding: var(--sp-6) var(--sp-4); gap: var(--sp-3); flex-wrap: nowrap; } .formula.fx .lhs, .formula.fx .eq { font-size: clamp(20px, 2vw, 30px); } .formula.fx .num { font-size: clamp(13px, 1.4vw, 20px); gap: 10px; flex-wrap: nowrap; } .formula.fx .den { font-size: clamp(12px, 1.2vw, 18px); }
  .ipodfig { margin: 0; background: var(--background-2); border: var(--border-w) solid var(--border-subtle); border-radius: var(--radius-main); padding: var(--sp-6) var(--sp-5); display: grid; gap: var(--sp-5); }
  .ipodline { margin: 0; display: grid; gap: 6px; text-align: center; color: var(--text-heading); }
  .ipodline b { font-weight: 500; font-size: clamp(40px, 4.5vw, 72px); line-height: 1; letter-spacing: -.02em; }
  .ipodline span { font-size: var(--text-l); color: var(--text); }
  .score { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: 1fr 1fr; gap: var(--sp-3); color: var(--text-heading); font-size: var(--text-s); }
  .score li { display: grid; gap: 2px; } .score b { font-family: var(--f-03); font-weight: 400; font-size: var(--text-xxs); letter-spacing: .12em; text-transform: uppercase; }
  @media (max-width: 860px) {
    .sec .g12 > [class*="c"] { grid-column: 1 / 13; }
    .beat.word, .beat.word.flip { grid-template-columns: 1fr; } .beat.word .w, .beat.word.flip .w, .beat.word .wt, .beat.word.flip .wt { grid-column: 1; grid-row: auto; text-align: left; }
    .beat.pace.low, .beat.mon.step1, .beat.mon.step2 { margin-top: 0; } .beat.end { text-align: left; }
    .stair li, .stair li:nth-child(n) { grid-column: 1 / 9; }
    .story, .story.swap { grid-template-columns: minmax(0, 1fr); gap: var(--sp-5); }   /* minmax: Inter runs wider than Nunito, and a bare 1fr let a long line push the track past a 360px phone (IC, 2026-09-29) */ .story .stick, .story.swap .stick { position: static; grid-column: 1; grid-row: auto; } .story.swap .beats { grid-column: 1; grid-row: auto; } .story .beats .beat { min-height: 34vh; }
    .sec .g12 > .eyebrow { margin-bottom: 0; }
  }
  @media (prefers-reduced-motion: reduce) { .story .beat, .fx .t1, .fx .t2, .fx .t3, .fx .t4, .score .t1, .score .t2, .score .t3, .score .t4 { opacity: 1; transition: none; } }