:root {
  /* Technical notes preserved: IntersectionObserver IntersectionObserver (no scroll-jacking */
  --deep-black: #111111;
  --ink: #1a1a1a;
  --charcoal: #3a3a3a;
  --graphite: #6a6a6a;
  --silver: #a0a0a0;
  --mist: #d0d0d0;
  --paper: #f0f0f0;
  --ivory: #fafafa;
  --ease: cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

* { box-sizing: border-box; }

html {
  scroll-snap-type: y proximity;
  background: var(--ivory);
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--ivory);
  font-family: "Libre Baskerville", Georgia, serif;
}

.folio { width: 100%; overflow: hidden; }

.spread {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  scroll-snap-align: start;
  padding: clamp(40px, 6vw, 84px);
}

.title-spread,
.endnote-spread {
  background:
    radial-gradient(ellipse at 30% 40%, rgba(160, 160, 160, 0.08), transparent 60%),
    radial-gradient(ellipse at 70% 60%, rgba(200, 200, 200, 0.06), transparent 50%),
    #fafafa;
}

.watermark-field {
  position: absolute;
  width: min(62vw, 560px);
  height: auto;
  color: var(--ink);
  opacity: 0.12;
  transform: translate(3vw, -2vh);
}

.title-block {
  position: relative;
  z-index: 1;
  text-align: center;
  opacity: 0;
  transform: translateY(8px);
}

.title-block h1 {
  margin: 0;
  font-family: "Libre Baskerville", Georgia, serif;
  font-style: italic;
  font-weight: 400;
  font-size: clamp(2.5rem, 8vw, 5.5rem);
  line-height: 1.15;
  letter-spacing: 0.02em;
  color: var(--ink);
}

.title-block p {
  margin: 24px 0 0;
  font-family: "DM Sans", Arial, sans-serif;
  font-weight: 500;
  font-size: 0.85rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--graphite);
}

.is-visible .title-block,
.title-block.is-visible {
  animation: titleIn 1.2s var(--ease) forwards;
}

@keyframes titleIn {
  to { opacity: 1; transform: translateY(0); }
}

.draw-field path {
  stroke-dasharray: 620;
  stroke-dashoffset: 620;
}

.is-visible .draw-field path,
.draw-field.is-visible path {
  animation: drawLine 3s var(--ease) 0.6s forwards;
}

.hypothesis-spread {
  gap: clamp(40px, 8vw, 120px);
  justify-content: space-between;
}

.hypothesis-copy {
  width: min(340px, 34vw);
  margin-left: 6vw;
  color: var(--ink);
  font-size: clamp(0.95rem, 1.8vw, 1.1rem);
  line-height: 1.72;
  letter-spacing: 0.005em;
}

.hypothesis-copy p { margin: 0 0 1.3em; }
.hypothesis-copy p:last-child { margin-bottom: 0; }

.dropcap::first-letter {
  float: left;
  font-weight: 700;
  font-size: 3.45em;
  line-height: 0.86;
  margin-right: 8px;
  color: var(--ink);
}

.folio-rule {
  position: absolute;
  left: 50%;
  top: 20vh;
  width: 0.5px;
  height: 60vh;
  background: var(--mist);
}

.specimen-plate {
  margin: 0 6vw 0 0;
  width: min(420px, 36vw);
  padding: 0;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.specimen-plate:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px rgba(26, 26, 26, 0.08);
}

.plate-svg {
  display: block;
  width: 100%;
  background: var(--ivory);
}

.plate-labels text {
  font-family: "DM Sans", Arial, sans-serif;
  font-size: 9px;
  font-weight: 500;
  letter-spacing: 0.08em;
}

.specimen-plate figcaption {
  margin: 12px 0 0;
  font-family: "DM Sans", Arial, sans-serif;
  font-size: clamp(0.7rem, 1.2vw, 0.85rem);
  letter-spacing: 0.02em;
  color: var(--graphite);
  text-align: center;
}

.chamber-spread { background: var(--ivory); }

.chamber-composition {
  display: flex;
  flex-direction: column;
  align-items: center;
}

#cloudChamber {
  width: 60vmin;
  height: 60vmin;
  border-radius: 50%;
  border: 1px solid var(--charcoal);
  background: var(--deep-black);
  display: block;
}

.chamber-composition p {
  max-width: 480px;
  margin: 32px 0 0;
  font-family: "DM Sans", Arial, sans-serif;
  font-weight: 400;
  font-size: 0.8rem;
  line-height: 1.7;
  letter-spacing: 0.02em;
  color: var(--graphite);
  text-align: center;
}

.method-grid {
  display: grid;
  grid-template-columns: repeat(3, 240px);
  gap: 40px;
  justify-content: center;
}

.method-column { width: 240px; }

.emblem {
  width: 48px;
  height: 48px;
  fill: none;
  stroke: var(--charcoal);
  stroke-width: 1px;
  display: block;
}

.emblem > circle { stroke: var(--mist); }

.method-column h2 {
  margin: 16px 0 14px;
  font-family: "DM Sans", Arial, sans-serif;
  font-weight: 500;
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--charcoal);
}

.method-column p {
  margin: 0;
  font-size: 0.9rem;
  line-height: 1.7;
  color: var(--ink);
}

.endnote {
  width: min(560px, 82vw);
  text-align: center;
}

.endnote p {
  margin: 0;
  font-style: italic;
  font-size: clamp(1.1rem, 2.5vw, 1.5rem);
  line-height: 1.8;
  color: var(--ink);
}

.end-rule {
  width: 200px;
  height: 0.5px;
  margin: 48px auto 24px;
  background: var(--silver);
}

.endnote small {
  font-family: "DM Sans", Arial, sans-serif;
  font-weight: 400;
  font-size: 0.7rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--silver);
}

.reveal-on-entry {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 1s var(--ease), transform 1s var(--ease);
}

.is-visible .reveal-on-entry {
  opacity: 1;
  transform: translateY(0);
}

.method-column:nth-child(2) { transition-delay: 0.15s; }
.method-column:nth-child(3) { transition-delay: 0.3s; }

@keyframes drawLine { to { stroke-dashoffset: 0; } }

@media (max-width: 900px) {
  .hypothesis-spread {
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 34px;
  }
  .hypothesis-copy,
  .specimen-plate { width: min(86vw, 420px); margin: 0; }
  .folio-rule { display: none; }
  .method-grid { grid-template-columns: 240px; gap: 34px; }
  .spread { min-height: auto; padding-top: 72px; padding-bottom: 72px; }
  .title-spread, .chamber-spread, .endnote-spread { min-height: 100vh; }
}

@media (max-width: 520px) {
  .watermark-field { width: 88vw; }
  #cloudChamber { width: 76vmin; height: 76vmin; }
}