:root {
  /* Compliance note: IBM Plex Mono* Mono** from Google Fonts; Source Serif 4* 4** from Google Fonts. */
  --parchment: #F4EAD6;
  --ivory: #FFF8E8;
  --ink: #2E261B;
  --sage: #8A9275;
  --sepia: #C9B58F;
  --clay: #B67858;
  --blue: #587C86;
  --brass: #C39A4A;
  --display: "Libre Baskerville", Georgia, serif;
  --body: "Source Serif 4", Georgia, serif;
  --mono: "IBM Plex Mono", monospace;
  --hand: "Caveat", cursive;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 72% 8%, rgba(195,154,74,.18), transparent 28rem),
    radial-gradient(circle at 18% 72%, rgba(88,124,134,.10), transparent 32rem),
    linear-gradient(115deg, var(--parchment), #efe0c2 70%, var(--parchment));
  font-family: var(--body);
  overflow-x: hidden;
}

.folio-grain {
  position: fixed;
  inset: 0;
  pointer-events: none;
  opacity: .33;
  z-index: 20;
  background-image:
    repeating-linear-gradient(0deg, rgba(46,38,27,.035) 0 1px, transparent 1px 7px),
    repeating-linear-gradient(90deg, rgba(201,181,143,.05) 0 1px, transparent 1px 11px);
  mix-blend-mode: multiply;
}

.margin-spine {
  position: fixed;
  inset: 0 auto 0 0;
  width: 26vw;
  min-width: 290px;
  padding: 34px 28px;
  background: linear-gradient(100deg, #ead9b8, var(--parchment) 62%, rgba(255,248,232,.84));
  border-right: 1px solid var(--sepia);
  box-shadow: 12px 0 35px rgba(46,38,27,.13);
  z-index: 10;
}

.margin-spine:before {
  content: "";
  position: absolute;
  right: 18px;
  top: 24px;
  bottom: 24px;
  border-right: 1px dashed rgba(88,124,134,.42);
}

.spine-tab {
  display: inline-block;
  padding: 9px 15px;
  margin-bottom: 34px;
  border: 1px solid var(--sepia);
  border-left: 5px solid var(--brass);
  background: rgba(255,248,232,.72);
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: .07em;
  transform: rotate(-1deg);
}

.mono-label, .ledger-row span, .chapter-link, .citation, .paper-tab {
  font-family: var(--mono);
  text-transform: lowercase;
  letter-spacing: .08em;
  font-size: 12px;
}

.spine-heading strong {
  display: block;
  margin-top: 8px;
  font-family: var(--display);
  font-size: clamp(28px, 3vw, 44px);
  line-height: 1;
  letter-spacing: -.035em;
}

.chapter-index {
  margin: 44px 0 38px;
  display: grid;
  gap: 7px;
}

.chapter-link {
  position: relative;
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 13px 14px 13px 0;
  color: var(--ink);
  text-decoration: none;
  border-bottom: 1px solid rgba(201,181,143,.55);
  transition: color .35s ease, transform .35s ease;
}

.chapter-link span {
  width: 36px;
  color: var(--blue);
}

.chapter-link:after {
  content: "";
  position: absolute;
  right: 6px;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--sepia);
  box-shadow: 0 0 0 6px rgba(195,154,74,0);
  transition: .35s ease;
}

.chapter-link.active { color: var(--clay); transform: translateX(6px); }
.chapter-link.active:after { background: var(--brass); box-shadow: 0 0 0 6px rgba(195,154,74,.16); }

.counter-ledger {
  padding: 18px 0;
  border-top: 1px solid var(--sepia);
  border-bottom: 1px solid var(--sepia);
}

.ledger-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 16px;
  padding: 10px 0;
}

.counter {
  font-family: var(--mono);
  font-weight: 500;
  color: var(--blue);
  font-size: 22px;
  font-variant-numeric: tabular-nums;
}

.spine-note {
  margin-top: 28px;
  color: var(--clay);
  font-size: 24px;
  transform: rotate(-3deg);
}

.handwritten { font-family: var(--hand); font-weight: 700; }
.tick-rail { position: absolute; bottom: 30px; left: 30px; right: 48px; display: flex; justify-content: space-between; }
.tick-rail i { width: 1px; height: 22px; background: var(--sepia); transform: rotate(8deg); }

.manuscript {
  margin-left: max(290px, 26vw);
  padding: 30px clamp(22px, 5vw, 74px) 70px;
}

.page {
  position: relative;
  min-height: calc(100vh - 60px);
  margin: 0 0 -24px;
  padding: clamp(42px, 7vw, 92px);
  background:
    linear-gradient(180deg, rgba(255,248,232,.92), rgba(255,248,232,.98)),
    repeating-linear-gradient(0deg, transparent 0 31px, rgba(201,181,143,.22) 32px);
  border: 1px solid rgba(201,181,143,.82);
  box-shadow: 0 24px 54px rgba(46,38,27,.15), inset 0 0 45px rgba(195,154,74,.08);
  transform: rotate(var(--tilt, .4deg));
  overflow: hidden;
  opacity: .72;
  transition: opacity .7s ease, transform .7s ease;
}

.page:nth-child(even) { --tilt: -.55deg; margin-left: clamp(0px, 2.4vw, 34px); }
.page.observed { opacity: 1; transform: rotate(0deg) translateY(0); }
.page:not(.observed) { transform: rotate(var(--tilt)) translateY(24px); }

.page:before {
  content: "";
  position: absolute;
  inset: 22px;
  border: 1px solid rgba(201,181,143,.35);
  pointer-events: none;
}

.kicker { color: var(--blue); margin: 0 0 22px; }
h1, h2 {
  font-family: var(--display);
  letter-spacing: -.035em;
  line-height: .98;
  margin: 0;
  max-width: 820px;
}
h1 { font-size: clamp(68px, 12vw, 164px); }
h2 { font-size: clamp(42px, 7vw, 92px); }
.lead, .page p {
  max-width: 720px;
  font-size: clamp(20px, 2vw, 29px);
  line-height: 1.48;
}
.page p:not(.kicker) { margin: 28px 0 0; }

.orbital-diagram {
  width: min(680px, 82%);
  margin: 38px 0 0 auto;
  color: var(--blue);
}
svg { overflow: visible; }
.orbit-line, .inline-mark circle, .star-map ellipse {
  fill: none;
  stroke: var(--blue);
  stroke-width: 1.7;
  stroke-dasharray: 4 7;
}
.faint { opacity: .45; stroke: var(--sage); }
.draw-line, .arrow, .inline-mark path, .star-map path {
  fill: none;
  stroke: var(--clay);
  stroke-width: 2.2;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-dasharray: 700;
  stroke-dashoffset: 700;
  transition: stroke-dashoffset 1.6s ease;
}
.observed .draw-line, .observed .arrow, .observed .inline-mark path, .observed .star-map path { stroke-dashoffset: 0; }
.orbit-dot { fill: var(--brass); filter: drop-shadow(0 1px 2px rgba(46,38,27,.25)); transform-origin: 50% 50%; }
.large-orbit .orbit-dot { animation: driftDot 8s linear infinite; }
svg text { font-family: var(--hand); font-size: 22px; fill: var(--clay); }

@keyframes driftDot { to { transform: rotate(360deg); } }

.margin-note {
  position: absolute;
  right: clamp(20px, 4vw, 64px);
  top: 30%;
  padding: 8px 14px;
  color: var(--clay);
  font-size: clamp(24px, 3vw, 38px);
  background: rgba(244,234,214,.56);
  border-bottom: 2px solid var(--sepia);
  transform: rotate(3deg);
  transition: transform .35s ease;
}
.margin-note:hover { transform: rotate(1deg) translateY(-4px); }
.note-one { top: auto; bottom: 18%; }

.paper-pin, .brass-weight {
  position: absolute;
  top: 34px;
  right: 46px;
  width: 17px;
  height: 17px;
  border-radius: 50%;
  background: radial-gradient(circle at 34% 30%, #f0d17a, var(--brass));
  box-shadow: 0 2px 8px rgba(46,38,27,.24);
}
.page-corner {
  position: absolute;
  right: 0;
  bottom: 0;
  border-width: 0 0 72px 72px;
  border-style: solid;
  border-color: transparent transparent var(--parchment) transparent;
  filter: drop-shadow(-4px -4px 8px rgba(46,38,27,.13));
  transition: transform .35s ease;
}
.page:hover .page-corner { transform: translate(-5px, -5px); }
.paper-tape {
  position: absolute;
  top: 28px;
  left: 42%;
  width: 120px;
  height: 34px;
  background: rgba(201,181,143,.34);
  transform: rotate(-2deg);
}
.annotation-cluster { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 34px; }
.citation {
  border: 1px solid var(--sepia);
  padding: 10px 13px;
  background: rgba(244,234,214,.68);
  color: var(--blue);
}
.citation.clay { color: var(--clay); }
.citation.sage { color: var(--sage); }
.inline-mark { width: min(480px, 86%); margin-top: 34px; }

.two-column-note {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(240px, 340px);
  gap: clamp(28px, 5vw, 70px);
  align-items: center;
}
.instrument-card {
  padding: 28px;
  border: 1px solid var(--sepia);
  background: rgba(244,234,214,.52);
  box-shadow: 12px 12px 0 rgba(201,181,143,.22);
}
.method-list { list-style: none; padding: 0; margin: 36px 0 0; max-width: 720px; }
.method-list li { display: flex; gap: 18px; padding: 18px 0; border-top: 1px solid rgba(201,181,143,.65); font-size: 23px; }
.method-list span { font-family: var(--mono); color: var(--blue); font-size: 13px; padding-top: 8px; }

.paper-tab {
  position: absolute;
  top: 110px;
  right: -1px;
  padding: 12px 18px;
  background: var(--clay);
  color: var(--ivory);
}
.revision-stack { position: relative; margin-top: 42px; min-height: 320px; }
.revision-stack article {
  position: absolute;
  width: min(520px, 78%);
  padding: 24px;
  border: 1px solid var(--sepia);
  background: var(--ivory);
  box-shadow: 0 14px 30px rgba(46,38,27,.12);
  transition: transform .35s ease;
}
.revision-stack article:nth-child(1) { left: 0; top: 0; transform: rotate(-2deg); }
.revision-stack article:nth-child(2) { left: 80px; top: 88px; transform: rotate(1.5deg); }
.revision-stack article:nth-child(3) { left: 36px; top: 180px; transform: rotate(-.6deg); }
.revision-stack article:hover { transform: rotate(0deg) translateY(-6px); }
.revision-stack b { display: block; font-family: var(--mono); color: var(--blue); font-size: 12px; text-transform: lowercase; letter-spacing: .1em; margin-bottom: 9px; }
.revision-stack span { font-size: 24px; }

.closing-desk { min-height: 100vh; }
.desk-composition { position: relative; min-height: 360px; margin-top: 34px; }
.sheet {
  position: absolute;
  padding: 30px;
  background: var(--ivory);
  border: 1px solid var(--sepia);
  box-shadow: 0 18px 36px rgba(46,38,27,.14);
}
.sheet-a { left: 2%; top: 28px; width: 260px; transform: rotate(4deg); font-family: var(--mono); }
.sheet-b { right: 10%; top: 140px; width: 230px; transform: rotate(-8deg); font-size: 34px; color: var(--clay); }
.mini { display: block; margin-top: 18px; }
.star-map { position: absolute; inset: 0 4% auto auto; width: min(620px, 86%); opacity: .78; }
.star-map circle { fill: var(--brass); }
.last-line { font-size: clamp(34px, 6vw, 70px); color: var(--clay); max-width: 760px; transform: rotate(-1deg); }

@media (max-width: 900px) {
  .margin-spine {
    width: 100%;
    min-width: 0;
    height: 120px;
    padding: 14px 16px;
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 8px 16px;
    overflow: hidden;
  }
  .margin-spine:before, .counter-ledger, .spine-note, .tick-rail { display: none; }
  .spine-tab { margin: 0; align-self: start; }
  .spine-heading strong { font-size: 24px; }
  .chapter-index { grid-column: 1 / -1; display: flex; gap: 8px; margin: 0; overflow-x: auto; }
  .chapter-link { white-space: nowrap; padding: 8px 24px 8px 0; border-bottom: 0; }
  .manuscript { margin-left: 0; padding: 140px 14px 40px; }
  .page { padding: 44px 24px; min-height: calc(100vh - 150px); }
  .two-column-note { grid-template-columns: 1fr; }
  .margin-note { position: relative; display: inline-block; right: auto; top: auto; margin-top: 20px; }
  .revision-stack article { width: 92%; left: 0 !important; }
  .star-map { position: relative; width: 100%; }
}