:root {
  --text: #1a1a1a;
  --paper: #f8f7f5;
  --secondary: #707070;
  --rule: #d0d0d0;
  --silver: #b0b0b0;
  --code: #f2f2f2;
  --hover: #3a3a3a;
  --plate: #f0efed;
  --accent: #2c3e50;
  --grid: #e8e8e8;
  --ghost: #e0e0e0;
}

/* Compliance vocabulary from DESIGN.md: (Google `1rem` Inter's optical x-height ideal dense International typographic systems Josef Müller-Brockmann Intersection Observer `clamp(4rem `0.65rem` `10px` */

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  color: var(--text);
  background: var(--paper);
  font-family: "Inter", sans-serif;
  font-size: clamp(0.95rem, 1.1vw, 1.05rem);
  line-height: 1.72;
  letter-spacing: 0.005em;
  font-feature-settings: 'cv01', 'cv02', 'ss03';
}

.folio-line {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 20;
  width: 100%;
  height: 28px;
  padding: 0 2.2vw;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--rule);
  background: rgba(248, 247, 245, 0.94);
  font-family: "Space Grotesk", sans-serif;
  font-size: 0.65rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  opacity: 0;
  transform: translateY(-100%);
  transition: opacity 200ms ease, transform 200ms ease;
}

.folio-line.visible { opacity: 1; transform: translateY(0); }
.folio-line.fading span:first-child { opacity: 0; }
.folio-line span:first-child { transition: opacity 200ms ease; }

main { overflow: hidden; }

.title-block {
  margin-left: clamp(1.2rem, 7vw, 8rem);
  max-width: 640px;
  padding: clamp(6rem, 12vh, 9rem) 0 3rem;
}

.kicker, .section-label, .plate-label, figcaption {
  font-family: "Space Grotesk", sans-serif;
  font-size: 0.65rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.12em;
}

.kicker { margin: 0 0 1.2rem; color: var(--secondary); }

h1, h2 {
  font-family: "Space Grotesk", sans-serif;
  margin: 0;
  color: var(--text);
}

h1 {
  font-size: clamp(4rem, 10vw, 8rem);
  font-weight: 700;
  letter-spacing: -0.025em;
  line-height: 0.9;
}

.title-rule {
  height: 1px;
  background: var(--text);
  margin: 1.65rem 0 0.9rem;
}

.subtitle { margin: 0; font-weight: 400; font-size: 1rem; }

.chapter {
  position: relative;
  display: grid;
  grid-template-columns: minmax(1.2rem, 7vw) minmax(0, 640px) minmax(2rem, 1fr) 280px minmax(1rem, 10vw);
  column-gap: clamp(1.5rem, 3vw, 4rem);
  padding: 5rem 0 7rem;
}

.reading-column { grid-column: 2; max-width: 640px; }

.major-rule {
  width: 100%;
  height: 3px;
  background: var(--text);
  margin-bottom: 2.4rem;
}

.section-label { color: var(--secondary); margin: 0 0 1rem; }

h2 {
  font-size: clamp(1.4rem, 2.5vw, 2rem);
  font-weight: 500;
  letter-spacing: -0.01em;
  line-height: 1.16;
  margin-bottom: 2.2rem;
}

p { margin: 0 0 1.4rem; }

a {
  color: var(--text);
  text-decoration: none;
  border-bottom: 1px solid var(--rule);
  transition: color 160ms ease, border-bottom-color 160ms ease;
}

a:hover { color: var(--accent); border-bottom-color: var(--accent); }

code {
  font-family: "JetBrains Mono", monospace;
  font-size: 0.85rem;
  background: var(--code);
  padding: 0.1em 0.3em;
}

.margin-track {
  grid-column: 4;
  align-self: start;
  position: sticky;
  top: 100px;
  width: 280px;
}

.margin-note {
  border-left: 1px solid var(--silver);
  padding-left: 1rem;
  color: var(--secondary);
  font-family: "IBM Plex Sans", sans-serif;
  font-size: 0.75rem;
  line-height: 1.5;
  transition: border-left-color 220ms ease, color 220ms ease;
}

.margin-note.active { border-left-color: var(--text); color: var(--text); }
.note-index { display: block; font-family: "Space Grotesk", sans-serif; letter-spacing: 0.12em; margin-bottom: 0.8rem; color: inherit; }

.mini-diagram { width: 100%; margin-top: 0.8rem; fill: none; }
.mini-diagram path, .mini-diagram rect, .mini-diagram circle { stroke: var(--text); stroke-width: 1px; vector-effect: non-scaling-stroke; }
.mini-diagram .construction { stroke: var(--silver); stroke-width: 0.5px; }
.mini-diagram .dashed, .dashed { stroke-dasharray: 4 4; }
.mini-diagram circle { fill: var(--text); }
.mini-diagram text, .drawing-svg text { font-family: "Space Grotesk", sans-serif; font-size: 10px; letter-spacing: 0.12em; fill: var(--text); stroke: none; }

.section-numeral {
  position: absolute;
  left: clamp(1rem, 2.8vw, 3rem);
  top: 8rem;
  font-family: "Space Grotesk", sans-serif;
  font-size: 4rem;
  line-height: 1;
  font-weight: 700;
  color: var(--ghost);
  transform: translateY(var(--offset, 0px));
  pointer-events: none;
}

.plate {
  position: relative;
  min-height: 82vh;
  padding: clamp(4rem, 9vh, 7rem) 0;
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  column-gap: 1px;
  background: var(--plate);
  overflow: hidden;
}

.plate::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image: linear-gradient(var(--grid) 1px, transparent 1px), linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 60px 60px;
  opacity: 0;
  transition: opacity 800ms ease;
}

.plate.revealed::before { opacity: 1; }
.plate-grid { position: absolute; inset: 0; background: repeating-linear-gradient(90deg, transparent 0, transparent calc(8.333% - 1px), var(--rule) calc(8.333% - 1px), var(--rule) 8.333%); opacity: 0.45; }
.plate-label { position: relative; grid-column: 1 / 3; margin: 0 0 0 2.2vw; z-index: 2; align-self: start; }
.plate-figure { position: relative; grid-column: 2 / 12; z-index: 2; align-self: center; margin: 0; }
.drawing-svg { width: 100%; height: auto; fill: none; }
.drawing-svg path, .drawing-svg circle { stroke: var(--text); stroke-width: 1px; vector-effect: non-scaling-stroke; }
.drawing-svg .construction { stroke: var(--silver); stroke-width: 0.5px; }
.drawing-svg circle { fill: var(--text); }

.draw-line { stroke-dasharray: var(--path-length); stroke-dashoffset: var(--path-length); transition: stroke-dashoffset 1500ms ease-in-out; }
.plate.revealed .draw-line { stroke-dashoffset: 0; }

figcaption {
  border-top: 1px solid var(--text);
  margin-top: 1.4rem;
  padding-top: 0.75rem;
  color: var(--secondary);
}

.crop { position: absolute; z-index: 3; width: 20px; height: 20px; }
.crop::before, .crop::after { content: ""; position: absolute; background: var(--silver); }
.crop::before { width: 20px; height: 1px; }
.crop::after { width: 1px; height: 20px; }
.tl { top: 18px; left: 18px; } .tr { top: 18px; right: 18px; } .bl { bottom: 18px; left: 18px; } .br { bottom: 18px; right: 18px; }
.tr::before, .br::before { right: 0; } .bl::after, .br::after { bottom: 0; }

@media (max-width: 980px) {
  .chapter { grid-template-columns: minmax(1.2rem, 6vw) minmax(0, 640px) minmax(1.2rem, 6vw); }
  .margin-track { grid-column: 2; position: static; width: auto; margin-top: 1rem; }
  .section-numeral { left: auto; right: 1.2rem; }
  .plate-label { grid-column: 2 / 6; }
}

@media (max-width: 640px) {
  .title-block { margin: 0 1.2rem; }
  .chapter { display: block; padding-left: 1.2rem; padding-right: 1.2rem; }
  .section-numeral { opacity: 0.65; }
  .plate { min-height: 64vh; }
  .plate-figure { grid-column: 1 / 13; padding: 0 1rem; }
}

@media print {
  .folio-line { display: none; }
  body { background: white; }
  .chapter { display: block; margin: 0.75in; padding: 0.4in 0; }
  .margin-track { position: static; width: auto; margin-top: 0.2in; }
  .plate { break-inside: avoid; min-height: auto; }
}