/* Polymerase Chain Reaction lesson. All rules scoped under .pcr-* */
.pcr-sc { width: 100%; display: flex; flex-direction: column; align-items: center; gap: 10px; }
.pcr-sc > svg { display: block; width: 100%; max-width: 400px; height: auto; overflow: visible; }
.pcr-note { font-size: 12.5px; color: var(--faint); text-align: center; line-height: 1.35; max-width: 320px; }
.pcr-t { fill: var(--text); font: 600 13px var(--sans); text-anchor: middle; }
.pcr-t.dim { fill: var(--dim); }
.pcr-t.sm { font-size: 12px; }
.pcr-t.gold { fill: var(--gold); font-weight: 700; }
.pcr-t.start { text-anchor: start; }
.pcr-t.end { text-anchor: end; }
.pcr-hero img { width: 250px; max-width: 100%; max-height: 36vh; object-fit: contain; display: block; margin: 0 auto; filter: drop-shadow(0 18px 30px rgba(123,92,253,.35)); }
.pcr-glab { align-self: flex-start; font-size: 12px; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: var(--dim); }

/* partner letters */
.pcr-lad { width: 100%; max-width: 360px; display: flex; flex-direction: column; gap: 6px; }
.pcr-lrow { display: grid; grid-template-columns: repeat(8, 1fr); gap: 5px; }
.pcr-lt { display: grid; place-items: center; height: 42px; border-radius: 9px; font: 700 18px var(--mono); color: var(--text); background: rgba(169,155,255,.14); border: 1.5px solid var(--violet-bright); }
.pcr-lrow.blank .pcr-lt { color: var(--faint); background: transparent; border-style: dashed; border-color: var(--line-strong); }
.pcr-lt.in { background: rgba(63,214,154,.16); border-color: var(--mint); color: var(--mint); animation: pcr-pop .25s ease-out; }
@keyframes pcr-pop { 0% { transform: scale(.7); } 100% { transform: none; } }
.pcr-rungs { display: grid; grid-template-columns: repeat(8, 1fr); gap: 5px; height: 16px; }
.pcr-rungs i { justify-self: center; width: 3px; background: var(--line-strong); border-radius: 2px; }
.choices.pcr-mono .choice span { font-family: var(--mono); letter-spacing: .12em; }

/* the machine */
.pcr-mac { touch-action: none; }
.pcr-band { fill: none; stroke: rgba(252,192,80,.35); stroke-width: 1.2; stroke-dasharray: 4 4; }
.pcr-st { fill: none; stroke-width: 4; stroke-linecap: round; }
.pcr-st.old { stroke: var(--violet-bright); }
.pcr-st.new { stroke: var(--mint); }
.pcr-rung { fill: none; stroke: rgba(169,155,255,.55); stroke-width: 2.5; stroke-linecap: round; }
.pcr-rung.new { stroke: rgba(63,214,154,.6); }
.pcr-top, .pcr-bot { transition: transform .9s cubic-bezier(.3,.7,.3,1); }
.pcr-mac.melt .pcr-top { transform: translateY(-26px); }
.pcr-mac.melt .pcr-bot { transform: translateY(26px); }
.pcr-pr { fill: var(--gold); opacity: 0; transform: translateY(-14px); transform-box: fill-box; transition: opacity .25s, transform .35s cubic-bezier(.34,1.56,.64,1); }
.pcr-bot .pcr-pr { transform: translateY(14px); }
.pcr-mac.primed .pcr-pr { opacity: 1; transform: none; }
.pcr-ng { opacity: 0; }
.pcr-mac.copying .pcr-ng { opacity: 1; }
.pcr-cop { opacity: 0; transition: opacity .3s; }
.pcr-cop ellipse { fill: rgba(63,214,154,.3); stroke: var(--mint); stroke-width: 2; transition: fill .4s, stroke .4s; }
.pcr-crk { fill: none; stroke: var(--red); stroke-width: 2; opacity: 0; }
.pcr-mac.copying .pcr-cop { opacity: 1; }
.pcr-mac.copied .pcr-cop { opacity: .8; }
.pcr-mac.dead .pcr-cop { opacity: 1; }
.pcr-mac.dead .pcr-cop ellipse { fill: rgba(110,105,96,.35); stroke: var(--faint); }
.pcr-mac.dead .pcr-crk { opacity: 1; }
.pcr-mac.dead .pcr-ng { transform: translateY(6px); transition: transform .6s; }
.pcr-tube { fill: var(--surface); stroke: var(--line-strong); stroke-width: 1.5; }
.pcr-bulb, .pcr-merc { fill: #6a86ff; transition: fill .4s; }
.pcr-mac.hot .pcr-bulb, .pcr-mac.hot .pcr-merc { fill: #ff6b5a; }
.pcr-mac:not(.hot):not(.cool) .pcr-bulb, .pcr-mac:not(.hot):not(.cool) .pcr-merc { fill: var(--gold); }
.pcr-tick { stroke: var(--faint); stroke-width: 1.5; }
.pcr-temp { font: 700 13px var(--mono); }
.pcr-steps { display: flex; align-items: center; justify-content: center; gap: 6px; flex-wrap: wrap; }
.pcr-steps span { font-size: 12.5px; font-weight: 700; color: var(--faint); padding: 4px 9px; border-radius: 999px; border: 1px solid var(--line); transition: color .2s, border-color .2s; }
.pcr-steps span.on { color: var(--gold); border-color: var(--gold); }
.pcr-steps i { color: var(--faint); font-style: normal; }
.pcr-key { display: flex; gap: 12px; flex-wrap: wrap; justify-content: center; font-size: 12.5px; font-weight: 700; color: var(--dim); }
.pcr-key span { display: inline-flex; align-items: center; gap: 5px; }
.pcr-key i { width: 16px; height: 4px; border-radius: 2px; }
.pcr-key .old { background: var(--violet-bright); }
.pcr-key .pr { background: var(--gold); }
.pcr-key .new { background: var(--mint); }
.pcr-big { display: flex; align-items: baseline; gap: 8px; font-size: 13px; font-weight: 600; color: var(--dim); }
.pcr-big b { font: 700 22px var(--mono); color: var(--gold); }

/* the tube of copies */
.pcr-glass { fill: rgba(234,227,215,.04); stroke: var(--line-strong); stroke-width: 2; }
.pcr-bit rect { fill: var(--violet-bright); }
.pcr-bit rect.n { fill: var(--mint); }
.pcr-bit { opacity: 0; transition: opacity .3s; }
.pcr-fill.on .pcr-bit { opacity: 1; }
.pcr-bit:not(.long) rect { fill: var(--gold); }
.pcr-bit:not(.long) rect.n { fill: var(--gold-deep); }

/* 1985: the doses */
.pcr-doses { display: grid; grid-template-columns: repeat(10, 22px); gap: 10px 8px; justify-content: center; padding: 8px 0; }
.pcr-doses i { width: 22px; height: 28px; border-radius: 50% 50% 50% 50% / 60% 60% 40% 40%; border: 1.5px dashed var(--line-strong); transition: background .2s, border-color .2s; }
.pcr-doses i.on { background: rgba(63,214,154,.35); border: 1.5px solid var(--mint); }
.pcr-cap2 { font-size: 13px; font-weight: 700; color: var(--dim); }
.pcr-nbox { fill: var(--surface); stroke: var(--gold); stroke-width: 1.5; stroke-dasharray: 5 4; }
.pcr-photo img { width: 100%; max-width: 380px; max-height: 32vh; object-fit: cover; border-radius: 14px; display: block; margin: 0 auto; }

/* run it */
.pcr-run { cursor: pointer; --g: 0; }
.pcr-hit { fill: transparent; }
.pcr-run .pcr-glass { transition: fill .15s, stroke .15s; }
.pcr-run.h .pcr-glass { fill: rgba(255,107,90,.18); stroke: #ff6b5a; }
.pcr-run.c .pcr-glass { fill: rgba(106,134,255,.18); stroke: #6a86ff; }
.pcr-dots rect { fill: var(--gold); opacity: 0; transition: opacity .25s; }
.pcr-dots rect.on { opacity: 1; }
.pcr-glowc { fill: var(--gold); opacity: calc(var(--g) * .35); filter: blur(18px); pointer-events: none; }
.pcr-count { display: flex; gap: 26px; justify-content: center; }
.pcr-count div { display: flex; flex-direction: column; align-items: center; gap: 2px; }
.pcr-count span { font-size: 12px; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: var(--dim); }
.pcr-count b { font: 700 22px var(--mono); color: var(--gold); }

/* the swab */
.pcr-well { fill: rgba(234,227,215,.04); stroke: var(--line-strong); stroke-width: 1.5; }
.pcr-hum { fill: none; stroke: var(--violet-bright); stroke-width: 2.5; stroke-linecap: round; opacity: .6; transition: opacity .5s; }
.pcr-vir { fill: none; stroke: #ff8a8a; stroke-width: 3.5; stroke-linecap: round; transition: stroke .4s; }
.pcr-t.pcr-vt { fill: #ff8a8a; }
.pcr-swab.pick .pcr-hum { opacity: .18; }
.pcr-swab.pick .pcr-vir { stroke: var(--gold); stroke-width: 5; }

/* the glow chart */
.pcr-ax { fill: none; stroke: var(--line-strong); stroke-width: 1.5; }
.pcr-thr { stroke: var(--gold); stroke-width: 1.5; stroke-dasharray: 5 4; }
.pcr-cv { fill: none; stroke-width: 3; stroke-dasharray: 1 1; stroke-dashoffset: 1; transition: stroke-dashoffset 1.4s ease-in-out; }
.pcr-cv.a { stroke: var(--mint); }
.pcr-cv.b { stroke: var(--violet-bright); transition-delay: .2s; }
.pcr-chart.drawn .pcr-cv { stroke-dashoffset: 0; }
.pcr-mk { opacity: 0; transition: opacity .3s 1.2s; }
.pcr-mk circle { fill: var(--gold); }
.pcr-t.pcr-la { fill: var(--mint); font-weight: 700; }
.pcr-t.pcr-lb { fill: var(--violet-bright); font-weight: 700; }
.pcr-chart.drawn .pcr-mk { opacity: 1; }
.pcr-hops path { fill: none; stroke: var(--gold); stroke-width: 2; opacity: 0; transition: opacity .2s; }
.pcr-chart.hop .pcr-hops path { opacity: 1; }
.pcr-x { opacity: 0; transition: opacity .3s .9s; }
.pcr-chart.hop .pcr-x { opacity: 1; }

/* the hair */
.pcr-h { fill: none; stroke: #c9a57a; stroke-width: 3; stroke-linecap: round; }
.pcr-root { fill: rgba(252,192,80,.3); stroke: var(--gold); stroke-width: 2; }

@media (max-height: 700px) {
  .pcr-sc { gap: 7px; }
  .pcr-sc > svg { max-width: 330px; }
  .pcr-lt { height: 36px; font-size: 16px; }
  .pcr-hero img { width: 200px; }
  .pcr-doses { grid-template-columns: repeat(10, 18px); gap: 8px 7px; }
  .pcr-doses i { width: 18px; height: 23px; }
}