/* ============================================================
   descent — an instrument, not a poster.
   Zero webfonts: system stacks only. Colour encodes depth and
   nothing else, so the ramp is data rather than decoration.
   ============================================================ */

:root {
  --step--2: clamp(0.68rem, 0.66rem + 0.09vw, 0.74rem);
  --step--1: clamp(0.80rem, 0.77rem + 0.14vw, 0.90rem);
  --step-0:  clamp(0.95rem, 0.92rem + 0.19vw, 1.08rem);
  --step-1:  clamp(1.15rem, 1.08rem + 0.32vw, 1.38rem);
  --step-2:  clamp(1.42rem, 1.28rem + 0.60vw, 1.85rem);
  --step-3:  clamp(1.80rem, 1.52rem + 1.20vw, 2.70rem);
  --display: clamp(2.4rem, 1.2rem + 5.2vw, 5.4rem);
  --readout: clamp(2.6rem, 1.4rem + 5.4vw, 5rem);

  --space-3xs: .25rem; --space-2xs: .5rem; --space-xs: .75rem;
  --space-s: 1rem;  --space-m: 1.5rem; --space-l: 2.5rem;
  --space-xl: 4rem; --space-2xl: 6rem;
  --space-3xl: clamp(6rem, 14vh, 11rem);

  --gutter: clamp(1.15rem, .6rem + 2.1vw, 3rem);
  --page: min(100% - var(--gutter) * 2, 1240px);
  --col: min(100% - var(--gutter) * 2, 40rem);

  /* ground */
  --void:    oklch(13.5% 0.022 255);
  --void-2:  oklch(17% 0.026 255);
  --ink:     oklch(94% 0.008 240);
  --ink-2:   oklch(72% 0.016 240);
  /* L55 measured 4.14:1 on --void — under the 4.5 floor, and the copy here
     sits on a translucent scrim over a scene that is sometimes bright, so
     it takes extra margin rather than the minimum. L61 measures 5.4:1. */
  --ink-3:   oklch(61% 0.020 245);
  --rule:    oklch(30% 0.030 250);
  --rule-2:  oklch(24% 0.026 252);

  /* the depth ramp — shallow is hot, deep is cold. This is the legend. */
  --shallow: oklch(78% 0.175 62);
  --mid:     oklch(74% 0.120 130);
  --deep:    oklch(74% 0.145 218);
  --alert:   oklch(68% 0.205 27);
  --focus:   oklch(80% 0.14 220);

  --dur-fast: .18s; --dur-base: .4s; --dur-slow: .9s;
  --ease-out: cubic-bezier(.22, 1, .36, 1);
  --ease-snap: cubic-bezier(.16, 1, .3, 1);

  --mono: ui-monospace, "SF Mono", "Cascadia Mono", "JetBrains Mono",
          "Roboto Mono", Menlo, Consolas, monospace;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }
body, h1, h2, p, dl, dd, ul, figure { margin: 0; padding: 0; }
ul { list-style: none; }
a { color: inherit; }

body {
  background: var(--void);
  color: var(--ink);
  font-family: var(--sans);
  font-size: var(--step-0);
  line-height: 1.62;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
::selection { background: var(--shallow); color: var(--void); }

/* ---- the instrument sits behind everything ---- */
#stage {
  position: fixed;
  inset: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  display: block;
  /* until JS decides otherwise, it is an empty dark plate — no flash */
  background:
    radial-gradient(120% 90% at 50% 0%, oklch(20% 0.04 250) 0%, transparent 60%),
    var(--void);
}
/* faint scanline tooth: register, not texture-for-its-own-sake */
.grain {
  position: fixed; inset: 0; z-index: 1; pointer-events: none;
  background: repeating-linear-gradient(
    to bottom, oklch(100% 0 0 / .012) 0 1px, transparent 1px 3px);
  mix-blend-mode: screen;
}

header, main, footer, .hud { position: relative; z-index: 2; }

/* ---- a11y furniture ---- */
.skip {
  position: absolute; left: var(--space-s); top: -4rem; z-index: 60;
  background: var(--ink); color: var(--void);
  padding: .7rem 1.1rem; font-family: var(--mono); font-size: var(--step--1);
  text-decoration: none;
  transition: top var(--dur-fast) var(--ease-out);
}
.skip:focus-visible { top: var(--space-s); }
:focus-visible { outline: 2px solid var(--focus); outline-offset: 3px; }

/* ---- header ---- */
.head {
  width: var(--page); margin-inline: auto;
  padding-block: var(--space-m);
  display: flex; flex-wrap: wrap; gap: var(--space-s);
  align-items: baseline; justify-content: space-between;
  font-family: var(--mono); font-size: var(--step--1);
}
.head__back { text-decoration: none; }
.head__back:hover { color: var(--shallow); }
.dim { color: var(--ink-3); }
.head__meta {
  font-size: var(--step--2); color: var(--ink-3);
  letter-spacing: .10em; text-transform: uppercase;
}

/* ---- the HUD: a depth gauge, fixed ---- */
.hud {
  position: fixed;
  right: var(--gutter);
  bottom: var(--space-l);
  z-index: 3;
  text-align: right;
  font-family: var(--mono);
  opacity: 0;
  transition: opacity var(--dur-base) var(--ease-out);
}
.hud.is-live { opacity: 1; }
/* the gauge gets its own pool of dark, or it sits on the brightest cluster */
.hud::before {
  content: "";
  position: absolute;
  inset: -1.5rem -2rem -2rem -3.5rem;
  z-index: -1;
  pointer-events: none;
  background: radial-gradient(120% 100% at 80% 40%,
    oklch(13.5% 0.022 255 / .88) 0%,
    oklch(13.5% 0.022 255 / .55) 55%,
    transparent 78%);
}
.hud__label {
  font-size: var(--step--2); letter-spacing: .16em;
  text-transform: uppercase; color: var(--ink-3);
}
.hud__value {
  font-size: var(--readout);
  line-height: .95;
  font-variant-numeric: tabular-nums;
  letter-spacing: -.03em;
  color: var(--shallow);
  transition: color var(--dur-slow) linear;
}
.hud.is-deep .hud__value { color: var(--deep); }
.hud__unit {
  font-size: var(--step-0); margin-left: .3em;
  color: var(--ink-3); letter-spacing: 0;
}
.hud__scale {
  position: relative;
  width: 2px; height: clamp(7rem, 22vh, 12rem);
  margin: var(--space-s) 0 0 auto;
  background: linear-gradient(to bottom, var(--shallow), var(--mid), var(--deep));
  opacity: .45;
}
.hud__tick {
  position: absolute; right: 10px; top: calc(var(--at) * 100%);
  transform: translateY(-50%);
  font-size: var(--step--2); color: var(--ink-3);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}
.hud__tick::before {
  content: ""; position: absolute; right: -10px; top: 50%;
  width: 6px; height: 1px; background: var(--rule);
}
.hud__head {
  position: absolute; left: -3px; top: 0;
  width: 8px; height: 8px; border-radius: 50%;
  background: var(--ink);
  transform: translateY(-50%);
  will-change: transform;
}
.hud__note {
  margin-top: var(--space-s);
  font-size: var(--step--2); color: var(--ink-3);
  letter-spacing: .04em;
}
@media (max-width: 60rem) {
  .hud { bottom: auto; top: 4.5rem; }
  .hud__scale { display: none; }
  .hud__value { font-size: var(--step-2); }
  .hud__note { display: none; }
}

/* ---- beats ---- */
.beat {
  position: relative;
  width: var(--page); margin-inline: auto;
  padding-block: var(--space-3xl);
  min-height: 100svh;
  display: flex; flex-direction: column; justify-content: center;
}
/* The scene is bright where the data is dense. Text never sits on it
   unprotected — a scrim rides behind whichever side the copy is on. */
.beat::before {
  content: "";
  position: absolute;
  /* exactly the gutters back, never more: --page is 100% - 2*gutter, so this
     reaches the viewport edge and stops. -50vw here cost a horizontal
     scrollbar on every phone. */
  inset: 0 calc(-1 * var(--gutter));
  z-index: -1;
  pointer-events: none;
  /* Sized to the copy, not to half the viewport: the text is safe and the
     scene keeps the room it needs to be worth looking at. */
  background: linear-gradient(to right,
    oklch(13.5% 0.022 255 / .90) 0%,
    oklch(13.5% 0.022 255 / .86) 30%,
    transparent 56%);
}
.beat[data-beat]::before { transform: scaleX(-1); }
.beat--table::before, .beat--colophon::before {
  background: oklch(13.5% 0.022 255 / .88);
}
.beat--open { min-height: 92svh; }
.eyebrow, .beat__mark {
  font-family: var(--mono); font-size: var(--step--2);
  letter-spacing: .16em; text-transform: uppercase; color: var(--ink-3);
}
.beat__mark { color: var(--shallow); }
.beat--floor .beat__mark, .beat--table .beat__mark { color: var(--deep); }

.title {
  font-size: var(--display);
  line-height: 1.0;
  letter-spacing: -.035em;
  font-weight: 700;
  margin-block: var(--space-m) var(--space-l);
  text-wrap: balance;
}
.beat__title {
  font-size: var(--step-3);
  line-height: 1.1;
  letter-spacing: -.02em;
  font-weight: 650;
  margin-block: var(--space-2xs) var(--space-m);
  max-width: 20ch;
  text-wrap: balance;
}
.lede {
  font-size: var(--step-1);
  max-width: 44ch;
  color: var(--ink-2);
  line-height: 1.5;
}
.beat__body { max-width: 46ch; color: var(--ink-2); }
.beat__body--wide { max-width: 60ch; }
.beat__body b, .lede b { color: var(--ink); font-weight: 600; }

.cue {
  margin-top: var(--space-2xl);
  font-family: var(--mono); font-size: var(--step--2);
  letter-spacing: .18em; text-transform: uppercase; color: var(--ink-3);
}

/* the reading beats sit right, so the scene stays legible left */
.beat[data-beat] { align-items: flex-end; text-align: left; }
.beat[data-beat] > * { width: min(100%, 34rem); }
@media (max-width: 60rem) {
  .beat[data-beat] { align-items: stretch; }
  .beat[data-beat] > * { width: 100%; }
  .beat { padding-block: var(--space-2xl); min-height: auto; }
  .beat--open { min-height: 80svh; }
}

/* ---- the floor event card ---- */
.event {
  border: 1px solid var(--rule);
  background: oklch(17% 0.026 255 / .72);
  backdrop-filter: blur(6px);
  padding: var(--space-m);
}
.event__data > div {
  display: grid; grid-template-columns: 8rem minmax(0, 1fr);
  gap: var(--space-s);
  padding-block: var(--space-2xs);
  border-bottom: 1px solid var(--rule-2);
}
.event__data dt {
  font-family: var(--mono); font-size: var(--step--2);
  letter-spacing: .1em; text-transform: uppercase; color: var(--ink-3);
}
.event__data dd { font-family: var(--mono); font-size: var(--step--1); }
.event__note {
  margin-top: var(--space-m);
  color: var(--ink-2); font-size: var(--step--1); line-height: 1.6;
}

/* ---- the inversion ---- */
.compare {
  display: grid; gap: var(--space-s);
  margin-bottom: var(--space-m);
}
.compare__col {
  border-top: 2px solid var(--deep);
  padding-top: var(--space-s);
}
.compare__col--alert { border-top-color: var(--alert); }
.compare__k {
  font-family: var(--mono); font-size: var(--step--2);
  letter-spacing: .12em; text-transform: uppercase; color: var(--ink-3);
}
.compare__v {
  font-family: var(--mono);
  font-size: clamp(2rem, 6vw, 3rem);
  line-height: 1.05;
  font-variant-numeric: tabular-nums;
  letter-spacing: -.02em;
  color: var(--deep);
}
.compare__col--alert .compare__v { color: var(--alert); }
.compare__v .u { font-size: var(--step-0); color: var(--ink-3); margin-left: .25em; }
.compare__m { font-family: var(--mono); font-size: var(--step--1); color: var(--ink-2); }
.compare__m b { color: var(--ink); }
.compare__p { font-size: var(--step--1); color: var(--ink-3); }
@media (min-width: 34rem) {
  .compare { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: var(--space-l); }
}

/* ---- the distribution: real bars, no library ---- */
.bands { margin-block: var(--space-l); display: grid; gap: var(--space-2xs); }
.band {
  display: grid;
  grid-template-columns: 8.5rem minmax(0, 1fr) 4rem 3.5rem;
  align-items: center;
  gap: var(--space-s);
  padding-block: var(--space-xs);
  border-bottom: 1px solid var(--rule-2);
  font-family: var(--mono);
  font-size: var(--step--1);
}
.band__range { color: var(--ink-2); }
.band__bar { display: block; height: 10px; background: var(--rule-2); }
.band__bar i {
  display: block; height: 100%;
  width: calc(var(--w) * 1%);
  background: var(--shallow);
  transform-origin: left;
}
.band--deep .band__bar i { background: var(--deep); }
.band__n, .band__pct { font-variant-numeric: tabular-nums; text-align: right; }
.band__pct { color: var(--ink-3); }
@media (max-width: 46rem) {
  .band { grid-template-columns: 7rem minmax(0, 1fr) 3.5rem; }
  .band__pct { display: none; }
}

/* ---- colophon ---- */
.creds { margin-block: var(--space-l); }
.creds > div {
  display: grid; grid-template-columns: 8rem minmax(0, 1fr);
  gap: var(--space-s);
  padding-block: var(--space-2xs);
  border-bottom: 1px solid var(--rule-2);
}
.creds dt {
  font-family: var(--mono); font-size: var(--step--2);
  letter-spacing: .1em; text-transform: uppercase; color: var(--ink-3);
}
.creds dd { font-size: var(--step--1); color: var(--ink-2); }
code {
  font-family: var(--mono); font-size: .92em;
  background: var(--void-2); padding: .1em .35em; border-radius: 2px;
  color: var(--ink);
}
.cta {
  align-self: flex-start;
  margin-top: var(--space-m);
  font-family: var(--mono); font-size: var(--step--1);
  text-decoration: none;
  border-bottom: 2px solid var(--shallow);
  padding-bottom: 2px;
  transition: color var(--dur-fast) var(--ease-out);
}
.cta:hover { color: var(--shallow); }

.foot {
  width: var(--page); margin-inline: auto;
  padding-block: var(--space-l) var(--space-2xl);
  border-top: 1px solid var(--rule-2);
  display: flex; flex-wrap: wrap; gap: var(--space-s);
  justify-content: space-between;
  font-family: var(--mono); font-size: var(--step--2); color: var(--ink-3);
}

/* ---- reveals: on by default, JS opts into hiding ---- */
.js [data-beat] > *, .js .beat--table > *, .js .beat--colophon > * { opacity: 0; }
.js .is-in > * {
  opacity: 1;
  transition: opacity var(--dur-base) var(--ease-out);
}
.js .is-in > *:nth-child(2) { transition-delay: .06s; }
.js .is-in > *:nth-child(3) { transition-delay: .12s; }

/* ---- reduced motion: the instrument holds still, the data stays ---- */
@media (prefers-reduced-motion: reduce) {
  .js [data-beat] > *, .js .beat--table > *, .js .beat--colophon > * {
    opacity: 1; transition: none;
  }
  .hud { opacity: 1; }
  .grain { display: none; }
  *, *::before, *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
  }
}