/* =====================================================================
   KINESIS — a self-describing field guide to the scroll-narrative
   Aurora Light system. Hand-authored. Motion gated on .motion;
   full prefers-reduced-motion fallback. Transform/opacity only.
   ===================================================================== */

/* ---------- tokens ---------- */
:root {
  --bg:        #07090F;
  --bg-2:      #0B0E17;
  --surface:   rgba(255, 255, 255, 0.035);
  --surface-2: rgba(255, 255, 255, 0.055);

  --bone:      #ECEDF4;
  --bone-dim:  #B8BBCB;
  --muted:     #8B90A7;
  --faint:     #565B73;

  --line:        rgba(255, 255, 255, 0.10);
  --line-soft:   rgba(255, 255, 255, 0.055);
  --line-strong: rgba(255, 255, 255, 0.20);

  /* aurora hues */
  --violet:  #7C5CFF;
  --indigo:  #6E7BFF;
  --blue:    #3E8BFF;
  --teal:    #2BD7C4;
  --aqua:    #39E0A0;
  --amber:   #FFB23E;
  --rose:    #FF6B9A;
  --magenta: #C66BFF;
  --cyan:    #39D2FF;

  /* live accent — JS mirrors the active chapter's hue here for fixed chrome */
  --glow: var(--violet);

  /* light side, for the contrast invert */
  --light-bg:  #ECEAE0;
  --light-ink: #0C0E16;

  --serif: "Fraunces", "Times New Roman", Georgia, serif;
  --sans:  "Inter", system-ui, -apple-system, sans-serif;
  --mono:  "JetBrains Mono", ui-monospace, "SFMono-Regular", monospace;

  --ease:      cubic-bezier(0.22, 1, 0.36, 1);
  --ease-soft: cubic-bezier(0.4, 0, 0.2, 1);
  --header-h:  4.5rem;

  --fs-cover: clamp(2.6rem, 8.2vw, 8rem);
  --fs-head:  clamp(2rem, 6vw, 5.4rem);
}

/* chapter / frame hue mapping — drives in-section accents even with no JS */
[data-glow="violet"]  { --glow: var(--violet); }
[data-glow="indigo"]  { --glow: var(--indigo); }
[data-glow="blue"]    { --glow: var(--blue); }
[data-glow="teal"]    { --glow: var(--teal); }
[data-glow="aqua"]    { --glow: var(--aqua); }
[data-glow="amber"]   { --glow: var(--amber); }
[data-glow="rose"]    { --glow: var(--rose); }
[data-glow="magenta"] { --glow: var(--magenta); }
[data-glow="cyan"]    { --glow: var(--cyan); }

/* ---------- reset ---------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  font-size: clamp(15px, 0.4vw + 13px, 19px);
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}
html.motion { scroll-behavior: auto; }

body {
  font-family: var(--sans);
  color: var(--bone-dim);
  background: var(--bg);
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
ul, ol { list-style: none; }
code { font-family: var(--mono); font-size: 0.88em; color: var(--bone); background: var(--surface-2); padding: 0.1em 0.45em; border-radius: 4px; }
button { font: inherit; color: inherit; background: none; border: none; cursor: pointer; }

::selection { background: color-mix(in srgb, var(--glow) 70%, transparent); color: #fff; }

:focus-visible { outline: 2px solid var(--glow); outline-offset: 3px; border-radius: 3px; }

.skip-link {
  position: fixed; top: 0; left: 50%; transform: translate(-50%, -120%);
  z-index: 400; background: var(--glow); color: #08060f;
  padding: 0.6rem 1.2rem; border-radius: 0 0 8px 8px;
  font-family: var(--mono); font-size: 0.74rem; letter-spacing: 0.06em;
  text-transform: uppercase; transition: transform 0.25s var(--ease);
}
.skip-link:focus { transform: translate(-50%, 0); }

.reveal, .word { will-change: opacity, transform; }
.muted { color: var(--muted); }
.em { font-style: italic; color: var(--bone); }
.em em { color: var(--glow); font-style: italic; }

/* =====================================================================
   ATMOSPHERE — aurora blooms, grain, pointer glow
   ===================================================================== */
.atmosphere { position: fixed; inset: 0; z-index: 0; pointer-events: none; overflow: hidden; }

.aurora {
  position: absolute; border-radius: 50%; filter: blur(80px);
  mix-blend-mode: screen; opacity: 0.5; will-change: transform;
}
.aurora--1 {
  width: 62vw; height: 62vw; top: -16vw; left: -12vw;
  background: radial-gradient(circle, color-mix(in srgb, var(--glow) 85%, transparent), transparent 64%);
  transition: background 1.2s var(--ease-soft);
}
.aurora--2 {
  width: 50vw; height: 50vw; bottom: -14vw; right: -10vw;
  background: radial-gradient(circle, rgba(43, 215, 196, 0.55), transparent 64%);
}
.aurora--3 {
  width: 42vw; height: 42vw; top: 38%; left: 52%;
  background: radial-gradient(circle, rgba(255, 178, 62, 0.42), transparent 66%);
  opacity: 0.4;
}
.motion .aurora--1 { animation: drift1 26s var(--ease-soft) infinite alternate; }
.motion .aurora--2 { animation: drift2 32s var(--ease-soft) infinite alternate; }
.motion .aurora--3 { animation: drift3 22s var(--ease-soft) infinite alternate; }
@keyframes drift1 { to { transform: translate3d(6vw, 4vw, 0) scale(1.15); } }
@keyframes drift2 { to { transform: translate3d(-5vw, -3vw, 0) scale(1.2); } }
@keyframes drift3 { to { transform: translate3d(-4vw, 5vw, 0) scale(1.1); } }

.pointer-glow {
  position: absolute; top: 0; left: 0; width: 460px; height: 460px;
  margin: -230px 0 0 -230px; border-radius: 50%;
  background: radial-gradient(circle, color-mix(in srgb, var(--glow) 50%, transparent), transparent 60%);
  mix-blend-mode: screen; opacity: 0; transition: opacity 0.6s var(--ease-soft);
  will-change: transform;
}
.motion .pointer-glow { opacity: 0.5; }
@media (hover: none) { .pointer-glow { display: none; } }

.grain {
  position: absolute; inset: -50%;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='200' height='200'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.82' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
  opacity: 0.05; mix-blend-mode: overlay;
}

/* =====================================================================
   MASTHEAD
   ===================================================================== */
.masthead {
  position: fixed; inset: 0 0 auto 0; z-index: 200; height: var(--header-h);
  display: flex; align-items: center; justify-content: space-between;
  padding-inline: clamp(18px, 4vw, 48px);
  transition: background 0.5s var(--ease), backdrop-filter 0.5s var(--ease), box-shadow 0.5s var(--ease);
}
.masthead.is-scrolled {
  background: color-mix(in srgb, var(--bg) 72%, transparent);
  backdrop-filter: blur(14px) saturate(1.2);
  box-shadow: 0 1px 0 var(--line-soft);
}
.brand { display: inline-flex; align-items: baseline; gap: 0.55em; color: var(--bone); }
.brand__mark { color: var(--glow); font-size: 1.05em; line-height: 1; transition: color 0.6s var(--ease); }
.brand__word { font-family: var(--mono); font-weight: 700; letter-spacing: 0.34em; font-size: 0.8rem; }
.masthead__tag {
  font-family: var(--mono); font-size: 0.66rem; letter-spacing: 0.16em;
  text-transform: uppercase; color: var(--faint); display: none;
}
@media (min-width: 720px) { .masthead__tag { display: block; } }
.masthead__nav { display: none; gap: 0.85rem; font-family: var(--mono); font-size: 0.72rem; color: var(--muted); }
@media (min-width: 560px) { .masthead__nav { display: flex; } }
.masthead__nav a { position: relative; padding: 0.2em 0.1em; transition: color 0.3s var(--ease); }
.masthead__nav a:hover { color: var(--bone); }
.masthead__nav a::after {
  content: ""; position: absolute; left: 0; right: 0; bottom: -2px; height: 1px;
  background: var(--glow); transform: scaleX(0); transform-origin: left; transition: transform 0.3s var(--ease);
}
.masthead__nav a:hover::after { transform: scaleX(1); }

/* =====================================================================
   HUD — the self-describing telemetry layer
   ===================================================================== */
.hud {
  position: fixed; left: clamp(14px, 3vw, 32px); bottom: clamp(14px, 3vw, 30px);
  z-index: 200; width: min(82vw, 320px);
  padding: 0.95rem 1.05rem 1.1rem;
  background: color-mix(in srgb, var(--bg-2) 78%, transparent);
  border: 1px solid var(--line); border-radius: 12px;
  backdrop-filter: blur(16px) saturate(1.2);
  font-family: var(--mono);
  box-shadow: 0 18px 50px -24px rgba(0, 0, 0, 0.8);
  transition: transform 0.5s var(--ease), opacity 0.4s var(--ease);
}
.hud.is-min { transform: translateY(calc(100% - 2.9rem)); }
.hud__line--title { display: flex; align-items: baseline; gap: 0.5em; color: var(--bone); }
.hud__bullet { color: var(--glow); transition: color 0.6s var(--ease); }
.hud__num { font-weight: 700; color: var(--glow); font-size: 0.82rem; transition: color 0.6s var(--ease); }
.hud__name { font-weight: 500; letter-spacing: 0.02em; font-size: 0.86rem; }
.hud__spec {
  margin-top: 0.4rem; font-size: 0.68rem; line-height: 1.5; color: var(--muted);
  letter-spacing: 0.01em; min-height: 2.1em;
}
.hud__readout {
  margin-top: 0.7rem; display: flex; flex-wrap: wrap; gap: 0.5rem 0.9rem;
  font-size: 0.64rem; letter-spacing: 0.04em; color: var(--faint); text-transform: uppercase;
}
.hud__readout b { color: var(--bone-dim); font-weight: 500; }
.hud__metric--x b { color: var(--glow); }
.hud__bar { margin-top: 0.7rem; height: 2px; background: var(--line); border-radius: 2px; overflow: hidden; }
.hud__bar span { display: block; height: 100%; width: 0; background: var(--glow); transition: width 0.15s linear, background 0.6s var(--ease); }
.hud__toggle {
  position: absolute; top: 0.55rem; right: 0.6rem; width: 1.6rem; height: 1.6rem;
  display: grid; place-items: center; color: var(--muted); font-size: 1rem; line-height: 1;
  border: 1px solid var(--line); border-radius: 6px; transition: color 0.3s, border-color 0.3s;
}
.hud__toggle:hover { color: var(--bone); border-color: var(--line-strong); }
@media (max-width: 460px) { .hud__spec { display: none; } .hud { width: min(86vw, 300px); } }

/* =====================================================================
   RAIL — vertical chapter index (right edge)
   ===================================================================== */
.rail {
  position: fixed; right: clamp(14px, 2.2vw, 30px); top: 50%; transform: translateY(-50%);
  z-index: 200; display: none; flex-direction: column; gap: 0.95rem;
}
@media (min-width: 1120px) { .rail { display: flex; } }
.rail__tick { display: flex; align-items: center; gap: 0.7rem; justify-content: flex-end; }
.rail__dot {
  width: 8px; height: 8px; border-radius: 50%; border: 1px solid var(--line-strong);
  background: transparent; transition: background 0.4s var(--ease), border-color 0.4s var(--ease), transform 0.4s var(--ease);
  flex: 0 0 auto;
}
.rail__label {
  font-family: var(--mono); font-size: 0.66rem; letter-spacing: 0.05em; color: var(--muted);
  opacity: 0; transform: translateX(6px); transition: opacity 0.3s var(--ease), transform 0.3s var(--ease);
  white-space: nowrap; text-align: right; order: -1;
}
.rail__tick:hover .rail__label { opacity: 1; transform: none; }
.rail__tick.is-active .rail__dot { background: var(--glow); border-color: var(--glow); transform: scale(1.4); box-shadow: 0 0 14px var(--glow); }
.rail__tick.is-active .rail__label { opacity: 1; transform: none; color: var(--bone); }

/* =====================================================================
   SHARED chapter scaffolding
   ===================================================================== */
.chapter { position: relative; z-index: 1; padding-block: clamp(6rem, 16vh, 13rem); }
.chapter__grid {
  max-width: 1280px; margin-inline: auto;
  padding-inline: clamp(20px, 5vw, 80px);
  display: grid; grid-template-columns: repeat(12, 1fr); column-gap: clamp(12px, 1.4vw, 26px);
  row-gap: clamp(1.6rem, 4vh, 3rem); align-items: start;
}
.tag {
  grid-column: 1 / -1; display: flex; align-items: center; gap: 0.9rem;
  font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.16em;
  text-transform: uppercase; color: var(--muted);
}
.tag__rule { width: clamp(28px, 5vw, 60px); height: 1px; background: var(--glow); display: inline-block; transition: background 0.6s var(--ease); }
.chapter__head {
  grid-column: 1 / -1; font-family: var(--serif); font-weight: 300; color: var(--bone);
  font-size: var(--fs-head); line-height: 0.98; letter-spacing: -0.012em;
}
.chapter__head span { display: block; }
.chapter__body { grid-column: 1 / span 7; font-size: clamp(1.02rem, 1.5vw, 1.22rem); color: var(--bone-dim); }
.chapter__body p + p { margin-top: 1.1rem; }
.chapter__body em { font-style: italic; color: var(--bone); }
.chapter__body a { color: var(--glow); border-bottom: 1px solid color-mix(in srgb, var(--glow) 45%, transparent); transition: border-color 0.3s; }
.chapter__body a:hover { border-color: var(--glow); }
@media (max-width: 820px) { .chapter__body { grid-column: 1 / -1; } }

/* annotation note — looks like a spec callout */
.note {
  grid-column: 8 / -1; align-self: start;
  border-left: 1px solid var(--line); padding: 0.2rem 0 0.2rem 1.2rem;
  font-size: 0.92rem; color: var(--muted);
}
.note--wide { grid-column: 1 / -1; max-width: 64ch; margin-top: 0.5rem; }
.note__fig { font-family: var(--mono); font-size: 0.66rem; letter-spacing: 0.1em; text-transform: uppercase; color: var(--glow); margin-bottom: 0.5rem; }
.note strong { color: var(--bone); font-weight: 500; }
@media (max-width: 820px) { .note { grid-column: 1 / -1; } }

/* demo frame */
.demo { grid-column: 1 / -1; position: relative; }
.demo__cap { font-family: var(--mono); font-size: 0.66rem; color: var(--faint); display: flex; flex-wrap: wrap; gap: 0.4rem 1.2rem; margin-top: 1rem; align-items: center; }
.demo__dot { width: 8px; height: 8px; border-radius: 50%; display: inline-block; margin-right: 0.3rem; vertical-align: -1px; }
.demo__dot--target { background: var(--bone-dim); }
.demo__dot--follow { background: var(--glow); }

/* reveal gating */
.motion [data-reveal] {
  opacity: 0; transform: translateY(24px);
  transition: opacity 0.9s var(--ease), transform 0.9s var(--ease);
  transition-delay: calc(var(--d, 0) * 70ms);
}
.motion [data-reveal].is-in { opacity: 1; transform: none; }

/* =====================================================================
   00 · COVER
   ===================================================================== */
.cover {
  position: relative; z-index: 1; min-height: 100svh;
  display: grid; align-content: center;
  padding: var(--header-h) clamp(20px, 5vw, 80px) clamp(9rem, 22vh, 14rem);
  max-width: 1280px; margin-inline: auto;
}
.cover__eyebrow {
  font-family: var(--mono); font-size: 0.74rem; letter-spacing: 0.22em;
  text-transform: uppercase; color: var(--muted); margin-bottom: clamp(1.4rem, 4vh, 2.6rem);
}
.cover__title { font-family: var(--serif); font-weight: 300; color: var(--bone); font-size: var(--fs-cover); line-height: 0.95; letter-spacing: -0.018em; }
.cover__line { display: block; }
.cover__line--strike { position: relative; width: max-content; color: var(--muted); }
.cover__line--strike::after {
  content: ""; position: absolute; left: -0.06em; right: -0.06em; top: 56%; height: 2px;
  background: var(--glow); transform: scaleX(0); transform-origin: left;
  transition: transform 0.7s var(--ease) 0.5s;
}
.motion .cover__line--strike.is-in::after { transform: scaleX(1); }
.cover__em em { font-style: italic; color: var(--glow); }
.cover__lede {
  max-width: 50ch; margin-top: clamp(1.6rem, 4vh, 2.6rem);
  font-size: clamp(1.05rem, 1.6vw, 1.32rem); color: var(--bone-dim);
}
.cover__lede strong { color: var(--bone); font-weight: 600; letter-spacing: 0.04em; }
.cover__lede em { color: var(--glow); font-style: italic; }
.cover__meta {
  display: flex; gap: 0.8rem; align-items: center; margin-top: 2rem;
  font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--faint);
}
.scroll-cue {
  position: absolute; bottom: clamp(18px, 4vh, 38px); left: 50%; transform: translateX(-50%);
  display: grid; justify-items: center; gap: 0.7rem; font-family: var(--mono); font-size: 0.66rem;
  letter-spacing: 0.22em; text-transform: uppercase; color: var(--muted);
}
.scroll-cue__rail { position: relative; width: 1px; height: 54px; background: var(--line-strong); overflow: hidden; }
.scroll-cue__rail i { position: absolute; top: -50%; left: 0; width: 100%; height: 50%; background: var(--glow); }
.motion .scroll-cue__rail i { animation: cue 2.4s var(--ease-soft) infinite; }
@keyframes cue { 0% { top: -50%; } 60%, 100% { top: 100%; } }
@media (max-width: 760px) { .scroll-cue { display: none; } }   /* would sit under the HUD on phones */

/* =====================================================================
   01 · THE GLIDE — follower easing toward a scroll-locked target
   ===================================================================== */
.glide-demo {
  margin-top: clamp(2rem, 5vh, 3.5rem); height: 130px;
  border: 1px solid var(--line); border-radius: 12px; background: var(--surface);
  overflow: hidden;
}
.glide-demo__track { position: absolute; left: 5%; right: 5%; top: 50%; height: 1px; background: var(--line); }
.glide-demo__target, .glide-demo__follow {
  position: absolute; top: 50%; border-radius: 50%; will-change: transform;
}
.glide-demo__target { width: 12px; height: 12px; margin: -6px 0 0 -6px; background: var(--bone-dim); }
.glide-demo__follow {
  width: 26px; height: 26px; margin: -13px 0 0 -13px;
  background: radial-gradient(circle, var(--glow), color-mix(in srgb, var(--glow) 10%, transparent) 70%);
  box-shadow: 0 0 26px var(--glow);
}

/* =====================================================================
   02 · THE TYPE — one giant word, scaled + cropped by scroll
   ===================================================================== */
.type-stage {
  margin-top: clamp(2rem, 6vh, 5rem); display: grid; place-items: center;
  overflow: hidden; min-height: 38vh;
}
.type-word {
  font-family: var(--serif); font-weight: 400; font-size: clamp(3.2rem, 26vw, 23rem);
  line-height: 0.78; letter-spacing: -0.03em; white-space: nowrap;
  background: linear-gradient(180deg, var(--bone), color-mix(in srgb, var(--glow) 80%, var(--bone)));
  -webkit-background-clip: text; background-clip: text; color: transparent;
  will-change: transform;
}
.type-foot {
  max-width: 44ch; margin: clamp(2rem, 5vh, 3.5rem) auto 0; text-align: center;
  font-family: var(--serif); font-style: italic; font-size: clamp(1.2rem, 2.2vw, 1.7rem); color: var(--muted);
}

/* =====================================================================
   03 · THE REVEAL — staggered lines
   ===================================================================== */
.reveal-ch__head .word { display: inline-block; margin-right: 0.28em; }
.reveal-demo {
  grid-column: 1 / span 7; margin-top: clamp(1.5rem, 4vh, 2.5rem);
  border-top: 1px solid var(--line); display: grid;
}
@media (max-width: 820px) { .reveal-demo { grid-column: 1 / -1; } }
.reveal-demo__row {
  display: flex; align-items: baseline; gap: 1rem; padding: 0.85rem 0;
  border-bottom: 1px solid var(--line-soft); color: var(--bone);
  font-size: clamp(1.05rem, 1.8vw, 1.4rem); font-family: var(--serif);
}
.reveal-demo__i { font-family: var(--mono); font-size: 0.7rem; color: var(--glow); flex: 0 0 auto; }

/* =====================================================================
   04 · THE TURN — pinned, vertical scroll → horizontal travel
   ===================================================================== */
.turn { padding-bottom: clamp(4rem, 10vh, 8rem); }
.turn__intro { padding-bottom: clamp(2rem, 5vh, 4rem); }
.turn__stage { position: relative; }
.turn__viewport {
  position: relative; display: flex; align-items: center;
  overflow-x: auto; overflow-y: hidden; padding-block: clamp(1.5rem, 4vh, 3rem);
  scrollbar-width: none;
}
.turn__viewport::-webkit-scrollbar { display: none; }
.turn__rail {
  display: flex; gap: clamp(1.4rem, 2.6vw, 2.6rem); width: max-content;
  padding-inline: clamp(20px, 6vw, 9rem); will-change: transform;
}
.frame {
  flex: 0 0 auto; width: clamp(230px, 30vw, 360px); height: clamp(280px, 42vh, 420px);
  position: relative; border: 1px solid var(--line); border-radius: 16px;
  background: linear-gradient(160deg, var(--surface-2), transparent 70%);
  padding: clamp(1.4rem, 2.4vw, 2.2rem); display: flex; flex-direction: column; justify-content: flex-end;
  overflow: hidden; isolation: isolate;
}
.frame::before {
  content: ""; position: absolute; inset: 0; z-index: -1;
  background: radial-gradient(120% 80% at 50% -10%, color-mix(in srgb, var(--glow) 26%, transparent), transparent 60%);
}
.frame__no {
  font-family: var(--mono); font-size: 0.74rem; color: var(--glow);
  position: absolute; top: clamp(1.2rem, 2vw, 1.8rem); left: clamp(1.4rem, 2.4vw, 2.2rem); letter-spacing: 0.1em;
}
.frame__t { font-family: var(--serif); font-weight: 400; font-size: clamp(1.6rem, 2.6vw, 2.3rem); color: var(--bone); line-height: 1; }
.frame p { font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.04em; text-transform: uppercase; color: var(--muted); margin-top: 0.6rem; }
.frame--now { border-color: color-mix(in srgb, var(--glow) 55%, transparent); }

.turn__spot { display: none; }
.turn__hint {
  position: absolute; left: 50%; bottom: 0.5rem; transform: translateX(-50%);
  font-family: var(--mono); font-size: 0.66rem; letter-spacing: 0.1em; text-transform: uppercase; color: var(--faint);
  opacity: 0;
}

/* pinned mode (JS adds .turn-pin when there's room to travel) */
.turn-pin .turn__stage { height: 460vh; }
.turn-pin .turn__viewport {
  position: sticky; top: 0; height: 100vh; overflow: hidden; padding-block: 0;
}
.turn-pin .turn__rail { align-items: center; }
.turn-pin .turn__hint { opacity: 1; transition: opacity 0.6s var(--ease); }
.turn-pin .turn__spot {
  display: block; position: absolute; top: 50%; left: 0; width: 60vh; height: 60vh;
  margin: -30vh 0 0 -30vh; border-radius: 50%; pointer-events: none;
  background: radial-gradient(circle, color-mix(in srgb, var(--glow) 30%, transparent), transparent 62%);
  mix-blend-mode: screen; will-change: transform;
}

/* =====================================================================
   05 · THE CONTRAST — scroll-linked polarity invert (--c set by JS 0..1)
   ===================================================================== */
.contrast {
  --c: 0;
  background: color-mix(in srgb, var(--light-bg) calc(var(--c) * 100%), transparent);
  transition: background 0.1s linear;
}
.contrast__head, .contrast .chapter__head { color: color-mix(in srgb, var(--light-ink) calc(var(--c) * 100%), var(--bone)); }
.contrast .chapter__body { color: color-mix(in srgb, var(--light-ink) calc(var(--c) * 86%), var(--bone-dim)); }
.contrast .chapter__body em { color: color-mix(in srgb, var(--light-ink) calc(var(--c) * 100%), var(--bone)); }
.contrast .tag { color: color-mix(in srgb, var(--light-ink) calc(var(--c) * 70%), var(--muted)); }
.contrast .em { color: color-mix(in srgb, var(--light-ink) calc(var(--c) * 100%), var(--bone)); }
.contrast .em em { color: var(--glow); }   /* the single accent — unchanged in both worlds */
.contrast__accentline {
  grid-column: 1 / -1; display: flex; align-items: center; gap: 0.7rem;
  font-family: var(--mono); font-size: 0.74rem; letter-spacing: 0.08em; text-transform: uppercase;
  color: color-mix(in srgb, var(--light-ink) calc(var(--c) * 70%), var(--muted));
}
.contrast__swatch { width: 18px; height: 18px; border-radius: 5px; background: var(--glow); box-shadow: 0 0 16px var(--glow); }

/* =====================================================================
   06 · THE DEPTH — parallax planes
   ===================================================================== */
.depth { overflow: hidden; }
.depth__scene { position: absolute; inset: 0; z-index: 0; pointer-events: none; }
.depth__layer {
  position: absolute; font-family: var(--serif); font-style: italic; will-change: transform;
  font-weight: 300; letter-spacing: 0.02em;
}
.depth__layer--back { top: 18%; left: 6%; font-size: clamp(3rem, 12vw, 11rem); color: color-mix(in srgb, var(--glow) 14%, transparent); }
.depth__layer--mid  { top: 52%; right: 8%; font-size: clamp(2rem, 7vw, 6rem); color: color-mix(in srgb, var(--bone) 12%, transparent); }
.depth__layer--fore { bottom: 14%; left: 14%; font-size: clamp(1.4rem, 4vw, 3.4rem); color: color-mix(in srgb, var(--glow) 34%, transparent); }
.depth__grid { position: relative; z-index: 1; }

/* =====================================================================
   07 · THE REGISTER — same kit, two feelings
   ===================================================================== */
.register-machine {
  grid-column: 1 / -1; margin-top: clamp(1.5rem, 4vh, 2.5rem);
  border: 1px solid var(--line); border-radius: 16px; overflow: hidden;
  background: var(--surface); backdrop-filter: blur(6px);
}
.register-machine__switch { display: flex; border-bottom: 1px solid var(--line); }
.rswitch {
  flex: 1; padding: 1rem 1.2rem; text-align: left; font-family: var(--mono); font-weight: 700;
  letter-spacing: 0.1em; color: var(--muted); font-size: 0.92rem;
  display: flex; flex-direction: column; gap: 0.2rem; transition: background 0.4s var(--ease), color 0.4s var(--ease);
  border-right: 1px solid var(--line);
}
.rswitch:last-child { border-right: none; }
.rswitch span { font-weight: 400; font-size: 0.64rem; letter-spacing: 0.14em; text-transform: uppercase; color: var(--faint); }
.rswitch.is-active { color: var(--bone); background: color-mix(in srgb, var(--glow) 14%, transparent); }
.rswitch.is-active span { color: var(--glow); }
.register-machine__params { display: grid; grid-template-columns: 1fr; }
@media (min-width: 620px) { .register-machine__params { grid-template-columns: 1fr 1fr; } }
.register-machine__params > div {
  display: flex; justify-content: space-between; gap: 1rem; align-items: baseline;
  padding: 0.85rem clamp(1.1rem, 2.2vw, 1.6rem); border-bottom: 1px solid var(--line-soft);
}
.register-machine__params dt { font-family: var(--mono); font-size: 0.68rem; letter-spacing: 0.06em; text-transform: uppercase; color: var(--muted); flex: 0 0 auto; }
.register-machine__params dd { font-size: 0.92rem; color: var(--bone); text-align: right; transition: opacity 0.3s var(--ease); }

/* =====================================================================
   COLOPHON
   ===================================================================== */
.colophon {
  position: relative; z-index: 1; padding: clamp(6rem, 16vh, 13rem) clamp(20px, 5vw, 80px) 3rem;
  max-width: 1280px; margin-inline: auto; overflow: hidden;
}
.colophon__head { font-family: var(--serif); font-weight: 300; color: var(--bone); font-size: var(--fs-head); line-height: 1; letter-spacing: -0.01em; }
.colophon__head span { display: block; }
.colophon__recap {
  margin: clamp(2.5rem, 6vh, 4rem) 0; display: grid; gap: 0.7rem; max-width: 70ch;
  font-size: 1.02rem; color: var(--bone-dim);
}
.colophon__recap b { font-family: var(--mono); font-size: 0.8rem; letter-spacing: 0.04em; color: var(--glow); margin-right: 0.3em; }
.colophon__grid { display: grid; gap: 2rem; grid-template-columns: 1fr; padding-top: 2.5rem; border-top: 1px solid var(--line); }
@media (min-width: 760px) { .colophon__grid { grid-template-columns: repeat(3, 1fr); } }
.colophon__k { font-family: var(--mono); font-size: 0.68rem; letter-spacing: 0.12em; text-transform: uppercase; color: var(--glow); margin-bottom: 0.8rem; }
.colophon__col p:not(.colophon__k) { color: var(--muted); font-size: 0.96rem; }
.colophon__col em { color: var(--bone); font-style: italic; }
.colophon__wordmark {
  font-family: var(--serif); font-weight: 300; line-height: 0.8; letter-spacing: 0.02em;
  font-size: clamp(3.5rem, 19vw, 18rem); margin-top: clamp(3rem, 8vh, 6rem);
  background: linear-gradient(120deg, var(--violet), var(--teal) 45%, var(--amber));
  -webkit-background-clip: text; background-clip: text; color: transparent;
  opacity: 0.92; will-change: transform;
}
.colophon__foot {
  display: flex; flex-wrap: wrap; justify-content: space-between; gap: 1rem;
  margin-top: 2rem; padding-top: 1.6rem; border-top: 1px solid var(--line);
  font-family: var(--mono); font-size: 0.7rem; letter-spacing: 0.05em; color: var(--faint); text-transform: uppercase;
}
.colophon__foot a { color: var(--glow); }

/* =====================================================================
   REDUCED MOTION — hold still, stay legible, keep the telemetry text
   ===================================================================== */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition-duration: 0.001ms !important; }
  html { scroll-behavior: auto; }
  .aurora { opacity: 0.34; }
  .scroll-cue__rail i { display: none; }
  .type-word { font-size: clamp(3rem, 16vw, 12rem); }
}