:root {
  color-scheme: dark;
  --ink: #f6f2ea;
  --muted: #a8a7b5;
  --void: #03040a;
  --void-soft: #090b16;
  --blue: #55d9ff;
  --violet: #9477ff;
  --gold: #f0c779;
  --red: #ff6e78;
  --line: rgba(255, 255, 255, 0.14);
  --display: Georgia, "Times New Roman", serif;
  --sans: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --content: min(1180px, calc(100% - 48px));
}

* {
  box-sizing: border-box;
}

html {
  background: var(--void);
  scroll-behavior: smooth;
  scrollbar-color: var(--violet) var(--void);
}

body {
  margin: 0;
  overflow-x: hidden;
  background:
    radial-gradient(circle at 18% 8%, rgba(73, 83, 172, 0.12), transparent 25rem),
    radial-gradient(circle at 87% 31%, rgba(89, 54, 166, 0.1), transparent 28rem),
    var(--void);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.7;
  text-rendering: optimizeLegibility;
}

body::before {
  position: fixed;
  z-index: -1;
  inset: 0;
  background-image:
    radial-gradient(circle at 17% 24%, rgba(255, 255, 255, 0.54) 0 0.6px, transparent 0.9px),
    radial-gradient(circle at 63% 71%, rgba(85, 217, 255, 0.34) 0 0.7px, transparent 1px),
    radial-gradient(circle at 86% 14%, rgba(255, 255, 255, 0.35) 0 0.6px, transparent 0.9px);
  background-size: 157px 157px, 211px 211px, 263px 263px;
  content: "";
  opacity: 0.4;
  pointer-events: none;
}

::selection {
  background: rgba(85, 217, 255, 0.25);
  color: #fff;
}

a {
  color: inherit;
}

img {
  display: block;
  max-width: 100%;
}

button,
input,
a {
  -webkit-tap-highlight-color: transparent;
}

a:focus-visible,
input:focus-visible {
  outline: 2px solid var(--blue);
  outline-offset: 5px;
}

.skip-link {
  position: fixed;
  z-index: 100;
  top: 16px;
  left: 16px;
  padding: 10px 14px;
  transform: translateY(-180%);
  background: var(--ink);
  color: var(--void);
  font-weight: 700;
  text-decoration: none;
}

.skip-link:focus {
  transform: translateY(0);
}

.reading-progress {
  position: fixed;
  z-index: 90;
  top: 0;
  right: 0;
  left: 0;
  height: 2px;
  background: rgba(255, 255, 255, 0.06);
}

.reading-progress span {
  display: block;
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--blue), var(--violet), var(--gold));
  box-shadow: 0 0 16px rgba(85, 217, 255, 0.8);
}

.site-header {
  position: absolute;
  z-index: 10;
  top: 0;
  right: 0;
  left: 0;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  width: var(--content);
  margin: 0 auto;
  padding: 28px 0;
  border-bottom: 1px solid rgba(255, 255, 255, 0.16);
  font-size: 11px;
  letter-spacing: 0.14em;
}

.site-header > p {
  margin: 0;
  color: var(--muted);
}

.site-header > p span {
  color: var(--gold);
}

.site-header nav {
  display: flex;
  justify-self: end;
  gap: 24px;
}

.site-header nav a {
  color: var(--muted);
  text-decoration: none;
  text-transform: uppercase;
  transition: color 180ms ease;
}

.site-header nav a:hover {
  color: var(--ink);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  width: fit-content;
  font-size: 14px;
  letter-spacing: 0.25em;
  text-decoration: none;
}

.brand b {
  color: var(--blue);
  font-weight: 700;
}

.brand-orbit {
  position: relative;
  display: inline-block;
  width: 25px;
  height: 25px;
  border: 1px solid rgba(85, 217, 255, 0.66);
  border-radius: 50%;
}

.brand-orbit::before {
  position: absolute;
  top: 50%;
  left: -5px;
  width: 33px;
  height: 8px;
  transform: translateY(-50%) rotate(-18deg);
  border: 1px solid rgba(148, 119, 255, 0.82);
  border-radius: 50%;
  content: "";
}

.brand-orbit::after {
  position: absolute;
  top: 2px;
  right: 1px;
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--gold);
  box-shadow: 0 0 8px var(--gold);
  content: "";
}

.hero {
  position: relative;
  min-height: 100svh;
  display: grid;
  align-items: end;
  overflow: hidden;
  isolation: isolate;
}

.hero-art {
  position: absolute;
  z-index: -2;
  inset: 0;
  margin: 0;
}

.hero-art img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center;
  animation: hero-breathe 18s ease-in-out infinite alternate;
}

.hero-shade {
  position: absolute;
  inset: 0;
  background:
    linear-gradient(90deg, rgba(3, 4, 10, 0.96) 0%, rgba(3, 4, 10, 0.68) 37%, rgba(3, 4, 10, 0.12) 70%),
    linear-gradient(0deg, var(--void) 0%, transparent 32%, rgba(3, 4, 10, 0.3) 100%);
}

@keyframes hero-breathe {
  from { transform: scale(1.01); }
  to { transform: scale(1.075); }
}

.hero-art figcaption {
  position: absolute;
  right: max(24px, calc((100vw - 1180px) / 2));
  bottom: 30px;
  max-width: 280px;
  color: rgba(255, 255, 255, 0.58);
  font-size: 10px;
  line-height: 1.5;
  letter-spacing: 0.12em;
  text-align: right;
  text-transform: uppercase;
}

.hero-art figcaption span,
figcaption span {
  color: var(--gold);
}

.hero-copy {
  width: var(--content);
  margin: 0 auto;
  padding: 170px 0 11vh;
}

.eyebrow,
.chapter-kicker {
  margin: 0 0 22px;
  color: var(--blue);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.22em;
  text-transform: uppercase;
}

.hero h1,
.correction h2,
.chapter h2,
.rubin-intro h2,
.rotation-lab h2,
.halo-reveal h2,
.evidence h2,
.unknown h2,
.answer h2,
.error-page h1 {
  margin: 0;
  font-family: var(--display);
  font-weight: 400;
  letter-spacing: -0.045em;
  line-height: 0.95;
}

.hero h1 {
  max-width: 880px;
  font-size: clamp(64px, 9.2vw, 152px);
}

h1 em,
h2 em {
  color: transparent;
  font-style: italic;
  -webkit-text-stroke: 1px rgba(246, 242, 234, 0.66);
}

.hero-deck {
  max-width: 600px;
  margin: 34px 0 38px;
  color: #d7d5dc;
  font-family: var(--display);
  font-size: clamp(20px, 2.2vw, 29px);
  line-height: 1.4;
}

.button {
  display: inline-flex;
  align-items: center;
  gap: 18px;
  min-height: 48px;
  padding: 13px 20px;
  border: 1px solid rgba(85, 217, 255, 0.55);
  background: rgba(5, 8, 19, 0.58);
  color: var(--ink);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-decoration: none;
  text-transform: uppercase;
  backdrop-filter: blur(10px);
  transition: background 180ms ease, border-color 180ms ease, transform 180ms ease;
}

.button:hover {
  transform: translateY(-2px);
  border-color: var(--blue);
  background: rgba(85, 217, 255, 0.12);
}

.scroll-cue {
  position: absolute;
  right: 25px;
  bottom: 170px;
  margin: 0;
  transform: rotate(90deg) translateX(100%);
  transform-origin: right bottom;
  color: rgba(255, 255, 255, 0.38);
  font-size: 9px;
  letter-spacing: 0.22em;
}

.section-shell {
  width: var(--content);
  margin: 0 auto;
}

.correction {
  position: relative;
  padding: 160px 0 150px;
}

.section-number {
  position: absolute;
  top: 100px;
  right: 0;
  color: rgba(255, 255, 255, 0.04);
  font-family: var(--display);
  font-size: clamp(120px, 20vw, 280px);
  line-height: 1;
  pointer-events: none;
}

.correction-copy {
  position: relative;
  max-width: 900px;
}

.correction h2,
.rubin-intro h2,
.rotation-lab h2,
.halo-reveal h2,
.evidence h2,
.unknown h2,
.answer h2 {
  font-size: clamp(48px, 7vw, 94px);
}

.lead {
  max-width: 760px;
  margin: 38px 0 0;
  color: #d5d2da;
  font-family: var(--display);
  font-size: clamp(22px, 2.5vw, 33px);
  line-height: 1.48;
}

.scale-compare {
  display: grid;
  grid-template-columns: 1fr 120px 1fr;
  gap: 30px;
  align-items: stretch;
  margin-top: 90px;
}

.scale-compare article {
  padding: 32px 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.scale-compare h3 {
  max-width: 380px;
  margin: 18px 0 14px;
  font-family: var(--display);
  font-size: 31px;
  font-weight: 400;
  line-height: 1.12;
}

.scale-compare p {
  max-width: 430px;
  margin: 0;
  color: var(--muted);
}

.year {
  color: var(--gold);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.2em;
}

.compare-axis {
  display: grid;
  place-items: center;
}

.compare-axis span {
  position: relative;
  width: 1px;
  height: 100%;
  min-height: 180px;
  background: linear-gradient(transparent, var(--violet), transparent);
}

.compare-axis span::after {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 11px;
  height: 11px;
  transform: translate(-50%, -50%);
  border: 1px solid var(--violet);
  border-radius: 50%;
  background: var(--void);
  box-shadow: 0 0 20px var(--violet);
  content: "";
}

.truth-note {
  display: grid;
  grid-template-columns: 170px 1fr;
  gap: 40px;
  align-items: baseline;
  margin-top: 50px;
  padding: 30px 0;
  border-top: 1px solid rgba(240, 199, 121, 0.45);
}

.truth-note span {
  color: var(--gold);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.2em;
}

.truth-note p {
  max-width: 780px;
  margin: 0;
  font-family: var(--display);
  font-size: clamp(24px, 3vw, 38px);
  line-height: 1.35;
}

.chapter {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(360px, 0.8fr);
  align-items: center;
  min-height: 820px;
  background: var(--void-soft);
}

.chapter:nth-of-type(even) {
  background: #05060d;
}

.chapter-art {
  position: relative;
  height: 100%;
  min-height: 820px;
  margin: 0;
  overflow: hidden;
}

.chapter-art::after,
.wide-art::after,
.halo-art::after,
.unknown-art::after,
.evidence-card figure::after {
  position: absolute;
  inset: 0;
  border: 1px solid rgba(255, 255, 255, 0.08);
  content: "";
  pointer-events: none;
}

.chapter-art img,
.wide-art img,
.halo-art img,
.unknown-art img,
.evidence-card img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 900ms cubic-bezier(.2, .8, .2, 1);
}

.chapter-art:hover img,
.wide-art:hover img,
.halo-art:hover img,
.unknown-art:hover img,
.evidence-card figure:hover img {
  transform: scale(1.025);
}

figcaption {
  position: absolute;
  right: 24px;
  bottom: 20px;
  left: 24px;
  padding-top: 12px;
  border-top: 1px solid rgba(255, 255, 255, 0.2);
  color: rgba(255, 255, 255, 0.63);
  font-size: 10px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  text-shadow: 0 2px 12px #000;
}

.chapter-copy {
  max-width: 590px;
  padding: 80px clamp(40px, 7vw, 110px);
}

.chapter-copy h2 {
  margin-bottom: 34px;
  font-size: clamp(46px, 5.4vw, 78px);
}

.chapter-copy h2 span {
  display: block;
  margin-bottom: 20px;
  color: var(--gold);
  font-family: var(--sans);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.18em;
}

.chapter-copy p {
  color: #bbb9c4;
}

.chapter-copy strong {
  color: var(--ink);
  font-weight: 600;
}

.source-link {
  display: inline-flex;
  gap: 14px;
  align-items: center;
  margin-top: 18px;
  padding-bottom: 6px;
  border-bottom: 1px solid rgba(85, 217, 255, 0.45);
  color: var(--blue);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.09em;
  text-decoration: none;
  text-transform: uppercase;
}

.source-link:hover {
  border-color: var(--blue);
}

.logic-list {
  margin: 26px 0;
  padding: 0;
  list-style: none;
}

.logic-list li {
  display: grid;
  grid-template-columns: 42px 1fr;
  gap: 14px;
  padding: 14px 0;
  border-top: 1px solid var(--line);
  color: #d9d6de;
}

.logic-list li:last-child {
  border-bottom: 1px solid var(--line);
}

.logic-list span {
  color: var(--violet);
  font-size: 11px;
  letter-spacing: 0.1em;
}

.small-note,
.model-warning {
  color: #858493 !important;
  font-size: 13px;
}

.rubin-intro {
  padding: 160px 0;
}

.rubin-quote {
  display: grid;
  grid-template-columns: 1fr 0.72fr;
  gap: 70px;
  align-items: end;
  margin-bottom: 70px;
}

.rubin-quote .eyebrow {
  grid-column: 1 / -1;
  margin-bottom: -30px;
}

.rubin-quote p:last-child {
  margin: 0 0 8px;
  color: var(--muted);
  font-size: 18px;
}

.wide-art {
  position: relative;
  height: min(68vw, 720px);
  min-height: 520px;
  margin: 0;
  overflow: hidden;
}

.rotation-lab {
  padding: 150px 0;
  border-top: 1px solid var(--line);
}

.lab-heading {
  display: grid;
  grid-template-columns: 1fr 0.75fr;
  gap: 60px;
  align-items: end;
  margin-bottom: 80px;
}

.lab-heading .chapter-kicker {
  grid-column: 1 / -1;
  margin-bottom: -32px;
}

.lab-heading p:last-child {
  margin: 0 0 8px;
  color: var(--muted);
  font-size: 18px;
}

.lab-layout {
  display: grid;
  grid-template-columns: minmax(0, 1.5fr) minmax(260px, 0.5fr);
  gap: 60px;
  align-items: center;
}

.curve-wrap {
  min-width: 0;
}

#rotation-curve {
  display: block;
  width: 100%;
  height: auto;
  overflow: visible;
}

.grid line {
  stroke: rgba(255, 255, 255, 0.1);
  stroke-width: 1;
}

.axis-labels text {
  fill: #7f7e8b;
  font-family: var(--sans);
  font-size: 11px;
}

.axis-labels .axis-title {
  fill: #a8a7b5;
  font-size: 9px;
  letter-spacing: 0.07em;
  text-anchor: middle;
}

.curve {
  fill: none;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-width: 4;
}

.visible-curve {
  stroke: var(--gold);
}

.observed-curve {
  stroke: var(--blue);
  filter: drop-shadow(0 0 6px rgba(85, 217, 255, 0.5));
}

.radius-guide {
  stroke: rgba(255, 255, 255, 0.4);
  stroke-dasharray: 4 5;
}

.curve-dot {
  stroke: var(--void);
  stroke-width: 3;
}

.visible-dot { fill: var(--gold); }
.observed-dot { fill: var(--blue); }

.curve-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 24px;
  padding-left: 78px;
  color: var(--muted);
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.curve-legend span {
  display: inline-flex;
  gap: 9px;
  align-items: center;
}

.legend-line {
  width: 28px;
  height: 3px;
}

.legend-line.visible { background: var(--gold); }
.legend-line.observed { background: var(--blue); box-shadow: 0 0 7px rgba(85, 217, 255, 0.6); }

.lab-control {
  padding: 32px 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.lab-control label {
  display: flex;
  flex-direction: column;
  gap: 5px;
  color: var(--muted);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.lab-control output {
  color: var(--ink);
  font-family: var(--display);
  font-size: 30px;
  font-weight: 400;
  letter-spacing: -0.02em;
  text-transform: none;
}

input[type="range"] {
  width: 100%;
  margin: 24px 0 35px;
  accent-color: var(--blue);
  cursor: grab;
}

input[type="range"]:active {
  cursor: grabbing;
}

.speed-readout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 18px;
}

.speed-readout p {
  margin: 0;
  padding-top: 15px;
  border-top: 1px solid var(--line);
}

.speed-readout span {
  display: block;
  min-height: 38px;
  color: var(--muted);
  font-size: 10px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.speed-readout strong {
  color: var(--gold);
  font-family: var(--display);
  font-size: 38px;
  font-weight: 400;
}

.speed-readout p:nth-child(2) strong {
  color: var(--blue);
}

.speed-readout small {
  margin-left: 3px;
  color: var(--muted);
}

#lab-conclusion {
  margin: 30px 0 10px;
  color: var(--ink);
  font-family: var(--display);
  font-size: 23px;
  line-height: 1.35;
}

.formula {
  margin: 28px 0;
  padding: 22px 0;
  border-top: 1px solid rgba(148, 119, 255, 0.45);
  border-bottom: 1px solid rgba(148, 119, 255, 0.45);
  color: var(--violet);
  font-family: var(--display);
  font-size: clamp(30px, 3.4vw, 48px);
  letter-spacing: 0.01em;
}

.formula .root-content {
  display: inline-block;
  padding-top: 4px;
  border-top: 1px solid var(--violet);
  color: var(--ink);
  font-size: 0.66em;
}

.doppler-list {
  margin: 30px 0;
}

.doppler-list > div {
  display: grid;
  grid-template-columns: 90px 1fr;
  gap: 18px;
  padding: 15px 0;
  border-top: 1px solid var(--line);
}

.doppler-list > div:last-child {
  border-bottom: 1px solid var(--line);
}

.doppler-list dt {
  color: var(--blue);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.15em;
}

.doppler-list > div:last-child dt {
  color: var(--red);
}

.doppler-list dd {
  margin: 0;
  color: var(--muted);
}

.halo-reveal {
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) minmax(340px, 0.6fr);
  gap: 70px;
  align-items: center;
  padding: 170px 0;
}

.halo-art {
  position: relative;
  aspect-ratio: 1.25;
  margin: 0;
  overflow: hidden;
}

.halo-copy p {
  color: var(--muted);
}

.halo-copy h2 {
  margin-bottom: 35px;
  font-size: clamp(48px, 5.5vw, 78px);
}

.matter-fact {
  margin: 35px 0;
  padding: 28px 0;
  border-top: 1px solid rgba(85, 217, 255, 0.4);
  border-bottom: 1px solid rgba(85, 217, 255, 0.4);
}

.matter-fact strong {
  display: block;
  color: var(--blue);
  font-family: var(--display);
  font-size: clamp(58px, 6vw, 86px);
  font-weight: 400;
  line-height: 1;
}

.matter-fact span {
  display: block;
  margin-top: 15px;
  color: #c9c7d0;
}

.evidence {
  padding: 150px 0;
  border-top: 1px solid var(--line);
}

.evidence-heading {
  display: grid;
  grid-template-columns: 1fr 0.72fr;
  gap: 70px;
  align-items: end;
  margin-bottom: 100px;
}

.evidence-heading .chapter-kicker {
  grid-column: 1 / -1;
  margin-bottom: -38px;
}

.evidence-heading > p:last-child {
  margin: 0 0 9px;
  color: var(--muted);
  font-size: 19px;
}

.evidence-card {
  display: grid;
  grid-template-columns: minmax(0, 1.25fr) minmax(300px, 0.75fr);
  gap: 70px;
  align-items: center;
  margin: 0 0 130px;
}

.evidence-card:last-child {
  margin-bottom: 0;
}

.evidence-card.reverse {
  grid-template-columns: minmax(300px, 0.75fr) minmax(0, 1.25fr);
}

.evidence-card.reverse figure {
  grid-column: 2;
  grid-row: 1;
}

.evidence-card figure {
  position: relative;
  aspect-ratio: 1.42;
  margin: 0;
  overflow: hidden;
}

.evidence-card h3 {
  margin: 14px 0 25px;
  font-family: var(--display);
  font-size: clamp(42px, 5vw, 72px);
  font-weight: 400;
  letter-spacing: -0.04em;
  line-height: 1;
}

.evidence-card p {
  color: var(--muted);
  font-size: 17px;
}

.evidence-index {
  color: var(--gold);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.18em;
}

.unknown {
  display: grid;
  grid-template-columns: minmax(360px, 0.75fr) minmax(0, 1.25fr);
  gap: 80px;
  align-items: center;
  padding: 160px 0;
}

.unknown-copy h2 {
  margin-bottom: 40px;
  font-size: clamp(47px, 5.7vw, 82px);
}

.unknown-copy p {
  color: var(--muted);
}

.unknown-copy .button {
  margin-top: 20px;
}

.unknown-art {
  position: relative;
  aspect-ratio: 1.38;
  margin: 0;
  overflow: hidden;
}

.answer {
  padding: 150px 0 170px;
  border-top: 1px solid var(--line);
  text-align: center;
}

.answer .eyebrow {
  color: var(--gold);
}

.answer-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 45px;
  margin-top: 90px;
  text-align: left;
}

.answer-grid p {
  margin: 0;
  padding-top: 24px;
  border-top: 1px solid var(--line);
  color: var(--muted);
}

.answer-grid span {
  display: block;
  margin-bottom: 15px;
  color: var(--blue);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.18em;
}

.site-footer {
  display: grid;
  grid-template-columns: 0.7fr 1fr 1.2fr;
  gap: 60px;
  width: var(--content);
  margin: 0 auto;
  padding: 70px 0 90px;
  border-top: 1px solid var(--line);
  color: #777684;
  font-size: 11px;
}

.site-footer > div:first-child p {
  margin-top: 18px;
}

.references {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.references p {
  margin: 0 0 10px;
  color: var(--gold);
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.16em;
}

.references a {
  width: fit-content;
  color: #aaa8b3;
  text-decoration-color: rgba(255, 255, 255, 0.25);
  text-underline-offset: 4px;
}

.references a:hover {
  color: var(--ink);
}

.art-credit {
  max-width: 410px;
  margin: 0;
}

.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity 700ms ease, transform 700ms cubic-bezier(.2, .8, .2, 1);
}

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

.error-page {
  min-height: 100svh;
  display: grid;
  place-items: center;
  padding: 30px;
  text-align: center;
}

.error-page main {
  max-width: 720px;
}

.error-page h1 {
  font-size: clamp(60px, 10vw, 120px);
}

.error-page main > p:not(.eyebrow) {
  max-width: 520px;
  margin: 32px auto;
  color: var(--muted);
  font-family: var(--display);
  font-size: 24px;
}

@media (max-width: 980px) {
  :root { --content: min(100% - 36px, 760px); }

  .site-header { grid-template-columns: 1fr auto; }
  .site-header > p { justify-self: end; }
  .site-header nav { display: none; }

  .hero-copy { padding-bottom: 14vh; }
  .hero-art figcaption { right: 18px; }
  .scroll-cue { display: none; }

  .scale-compare { grid-template-columns: 1fr; gap: 0; }
  .compare-axis { display: none; }
  .truth-note { grid-template-columns: 1fr; gap: 12px; }

  .chapter,
  .chapter:nth-of-type(even) { grid-template-columns: 1fr; }
  .chapter-art { width: 100%; height: auto; min-height: 0; aspect-ratio: 1.5; }
  .chapter-copy { max-width: none; padding: 90px max(24px, 7vw) 110px; }
  .chapter-gravity .chapter-copy,
  .chapter-spectrum .chapter-copy { grid-row: 2; }

  .rubin-quote,
  .lab-heading,
  .evidence-heading { grid-template-columns: 1fr; gap: 35px; }
  .rubin-quote .eyebrow,
  .lab-heading .chapter-kicker,
  .evidence-heading .chapter-kicker { margin-bottom: 0; }

  .lab-layout { grid-template-columns: 1fr; }
  .lab-control { max-width: 520px; }

  .halo-reveal,
  .unknown { grid-template-columns: 1fr; }
  .halo-copy { max-width: 680px; }
  .unknown-copy { grid-row: 1; }
  .unknown-art { grid-row: 2; }

  .evidence-card,
  .evidence-card.reverse { grid-template-columns: 1fr; gap: 38px; }
  .evidence-card.reverse figure { grid-column: 1; grid-row: 1; }

  .answer-grid { grid-template-columns: 1fr; gap: 24px; }
  .site-footer { grid-template-columns: 1fr 1fr; }
  .art-credit { grid-column: 1 / -1; }
}

@media (max-width: 620px) {
  :root { --content: calc(100% - 28px); }

  body { line-height: 1.62; }
  .site-header { padding: 20px 0; }
  .site-header > p { font-size: 9px; }
  .brand { font-size: 12px; }
  .brand-orbit { width: 22px; height: 22px; }
  .brand-orbit::before { width: 29px; left: -4px; }

  .hero { min-height: 820px; }
  .hero-art img { object-position: 60% center; }
  .hero-shade { background: linear-gradient(0deg, var(--void) 0%, rgba(3, 4, 10, 0.45) 42%, rgba(3, 4, 10, 0.42) 100%), linear-gradient(90deg, rgba(3, 4, 10, 0.72), transparent); }
  .hero-copy { padding: 150px 0 140px; }
  .hero h1 { font-size: clamp(58px, 18vw, 90px); }
  .hero-deck { font-size: 20px; }
  .hero-art figcaption { bottom: 16px; max-width: 240px; }

  .correction { padding: 110px 0; }
  .section-number { top: 60px; }
  .correction h2,
  .rubin-intro h2,
  .rotation-lab h2,
  .evidence h2,
  .answer h2 { font-size: clamp(45px, 13.6vw, 68px); }
  .lead { font-size: 21px; }
  .scale-compare { margin-top: 65px; }
  .truth-note p { font-size: 24px; }

  .chapter-art { width: 100%; min-height: 0; aspect-ratio: 1.12; }
  .chapter-copy { padding: 70px 24px 85px; }
  .chapter-copy h2 { font-size: 48px; }

  .rubin-intro,
  .rotation-lab,
  .halo-reveal,
  .evidence,
  .unknown,
  .answer { padding-top: 105px; padding-bottom: 105px; }
  .rubin-quote { margin-bottom: 48px; }
  .wide-art { min-height: 330px; height: 68vw; }

  .lab-heading { margin-bottom: 45px; }
  .lab-layout { gap: 34px; }
  .axis-labels .axis-title { font-size: 8px; }
  .curve-legend { padding-left: 0; gap: 14px; }
  .speed-readout { gap: 10px; }
  .speed-readout strong { font-size: 32px; }

  .halo-art,
  .unknown-art,
  .evidence-card figure { aspect-ratio: 1.1; }
  .halo-reveal,
  .unknown,
  .evidence-card { gap: 42px; }
  .halo-copy h2,
  .unknown-copy h2 { font-size: 50px; }
  .evidence-heading { margin-bottom: 65px; }
  .evidence-card { margin-bottom: 90px; }

  .answer-grid { margin-top: 60px; }
  .site-footer { grid-template-columns: 1fr; gap: 36px; }
  .art-credit { grid-column: 1; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    scroll-behavior: auto !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  .reveal { opacity: 1; transform: none; }
}