/* Curious Signals preview: "recorder paper".
   Ink on millimetre paper. Every value below traces back to the tokens in :root. */

@font-face {
  font-family: "Atkinson Hyperlegible Next";
  src: url("fonts/atkinson-hyperlegible-next.woff2") format("woff2");
  font-weight: 200 800;
  font-style: normal;
  font-display: swap;
}

@font-face {
  font-family: "Atkinson Hyperlegible Mono";
  src: url("fonts/atkinson-hyperlegible-mono.woff2") format("woff2");
  font-weight: 200 800;
  font-style: normal;
  font-display: swap;
}

/* ---------- Tokens ---------- */

:root {
  color-scheme: light;

  /* Surfaces and ink */
  --paper: #f5f3ec;          /* page */
  --sheet: #fbfaf6;          /* the recorder sheet and plot paper */
  --ink: #1a1c1f;            /* text, primary controls, white-channel pen */
  --ink-2: #45484d;          /* secondary text */
  --ink-3: #5f6267;          /* tertiary text, axis labels, control edges */
  --rule: #d5cfc1;           /* hairlines between regions */
  --ruling: #a63f12;         /* millimetre-paper ruling: active marker, playhead, accents */
  --grid-minor: #f1e1d4;
  --grid-major: #e0b293;
  --selection: #f3d4bf;

  /* Pens: phyphox channel colours translated to ink on paper */
  --pen-ink: var(--ink);
  --pen-green: #2e6a30;
  --pen-blue: #2552a6;
  --pen-ochre: #835700;      /* phyphox "yellow" */
  --pen-red: #b0261c;
  --pen-orange: #ad470f;

  /* Type */
  --font-text: "Atkinson Hyperlegible Next", ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: "Atkinson Hyperlegible Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --step--2: .75rem;         /* 12 */
  --step--1: .875rem;        /* 14 */
  --step-0: 1rem;            /* 16 */
  --step-1: 1.125rem;        /* 18 */
  --step-2: 1.375rem;        /* 22 */
  --step-3: 1.75rem;         /* 28 */
  --step-4: clamp(1.75rem, 1.2rem + 1.9vw, 2.5rem);   /* mode title */
  --step-5: clamp(2.125rem, 1.3rem + 3vw, 3.75rem);   /* page statement */
  --step-readout: clamp(1.875rem, 1.3rem + 2vw, 3rem);
  --leading-tight: 1.08;
  --leading-text: 1.5;

  /* Space: 8 px base, 40 px major, like 1 mm / 5 mm ruling */
  --s-1: 4px;
  --s-2: 8px;
  --s-3: 12px;
  --s-4: 16px;
  --s-5: 24px;
  --s-6: 32px;
  --s-7: 40px;
  --s-8: 64px;
  --s-9: 80px;
  --gutter: clamp(16px, 4vw, 40px);
  --measure: 62ch;
  --page-max: 1280px;
  --index-width: 252px;

  /* Lines, corners, depth */
  --hairline: 1px solid var(--rule);
  --edge: 1px solid var(--ink-3);
  --radius: 2px;             /* controls only; paper is square */
  --focus-ring: 3px solid var(--ink);
  --focus-offset: 3px;

  /* Motion: only the pen moves; controls change colour briefly */
  --duration-quick: 120ms;
  --ease-out: cubic-bezier(.2, 0, 0, 1);
}

@media (prefers-color-scheme: dark) {
  :root {
    color-scheme: dark;
    --paper: #131416;
    --sheet: #191a1d;
    --ink: #ebe7de;
    --ink-2: #c4c0b7;
    --ink-3: #a19d95;
    --rule: #36383c;
    --ruling: #ec8f5a;
    --grid-minor: #24211f;
    --grid-major: #4d3a2e;
    --selection: #5a3a26;
    --pen-green: #88c98b;
    --pen-blue: #98b6ff;
    --pen-ochre: #e0b45a;
    --pen-red: #ff9384;
    --pen-orange: #f39d68;
  }
}

/* ---------- Base ---------- */

*, *::before, *::after { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

body {
  margin: 0;
  min-width: 320px;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-text);
  font-size: var(--step-0);
  line-height: var(--leading-text);
  font-kerning: normal;
}

::selection { background: var(--selection); color: var(--ink); }

h1, h2, h3, p, ol, ul, dl, dd, figure { margin: 0; }
ol, ul { padding: 0; list-style: none; }

a {
  color: inherit;
  text-decoration-thickness: 1px;
  text-underline-offset: .22em;
  transition: text-decoration-color var(--duration-quick) var(--ease-out), color var(--duration-quick) var(--ease-out);
}
a:hover { text-decoration-color: var(--ruling); text-decoration-thickness: 2px; }

code, kbd, samp, output { font-family: var(--font-mono); }
code { font-size: .92em; }

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

:focus-visible {
  outline: var(--focus-ring);
  outline-offset: var(--focus-offset);
  border-radius: var(--radius);
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  top: var(--s-2);
  left: var(--s-2);
  z-index: 10;
  padding: var(--s-2) var(--s-3);
  background: var(--ink);
  color: var(--paper);
  font-weight: 700;
  text-decoration: none;
  transform: translateY(calc(-100% - var(--s-4)));
}
.skip-link:focus-visible { transform: none; outline-color: var(--ruling); }

/* Small mono label used for kickers, captions, and station numbers. */
.label {
  font-family: var(--font-mono);
  font-size: var(--step--2);
  font-weight: 500;
  letter-spacing: .02em;
  color: var(--ink-3);
}

.wrap {
  width: 100%;
  max-width: var(--page-max);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

/* ---------- Masthead ---------- */

.masthead {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--s-5);
  padding-block: var(--s-4);
  border-bottom: var(--hairline);
}

.wordmark {
  display: inline-flex;
  align-items: center;
  gap: var(--s-2);
  font-size: var(--step-1);
  font-weight: 800;
  letter-spacing: -.012em;
  text-decoration: none;
}
.wordmark svg { width: 28px; height: 20px; flex: none; }
.wordmark .mark-trace { fill: none; stroke: var(--ink); stroke-width: 2.2; stroke-linecap: round; stroke-linejoin: round; }
.wordmark .mark-pen { fill: var(--ruling); }

.masthead nav { display: flex; gap: var(--s-5); }
.masthead nav a {
  font-size: var(--step--1);
  font-weight: 600;
  text-decoration-color: transparent;
}
.masthead nav a:hover { text-decoration-color: var(--ruling); }

/* ---------- Statement ---------- */

.statement {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: end;
  gap: var(--s-5) var(--s-8);
  padding-block: var(--s-8) var(--s-7);
}

.statement h1 {
  max-width: 17ch;
  font-size: var(--step-5);
  font-weight: 750;
  line-height: var(--leading-tight);
  letter-spacing: -.028em;
  text-wrap: balance;
}

.statement-lede {
  max-width: 54ch;
  margin-top: var(--s-4);
  color: var(--ink-2);
  font-size: var(--step-1);
  text-wrap: pretty;
}

/* The board's facts as a spec plate. */
.spec {
  display: grid;
  grid-template-columns: auto auto;
  gap: var(--s-2) var(--s-5);
  padding: var(--s-4) 0 0;
  border-top: 2px solid var(--ink);
  font-size: var(--step--1);
}
.spec dt { color: var(--ink-3); font-family: var(--font-mono); font-size: var(--step--2); padding-top: 2px; }
.spec dd { font-family: var(--font-mono); font-weight: 600; }

/* ---------- Recorder: mode index + sheet ---------- */

.recorder {
  display: grid;
  grid-template-columns: var(--index-width) minmax(0, 1fr);
  border-top: 2px solid var(--ink);
}

.mode-index {
  min-width: 0;
  padding: var(--s-5) var(--s-5) var(--s-5) 0;
  border-right: var(--hairline);
}
.mode-index h2 { margin-bottom: var(--s-3); }

.mode-list { display: grid; }

.mode-button {
  position: relative;
  width: 100%;
  min-height: 56px;
  padding: var(--s-2) var(--s-3) var(--s-2) var(--s-4);
  border: 0;
  border-bottom: var(--hairline);
  border-radius: 0;
  background: var(--paper);
  color: var(--ink);
  display: grid;
  grid-template-columns: 32px minmax(0, 1fr);
  grid-template-rows: auto auto;
  column-gap: var(--s-2);
  align-items: baseline;
  text-align: left;
  cursor: pointer;
  /* No transition: a selector should switch like a detent, and a cross-fade passes through grey on grey. */
}
.mode-button:first-child { border-top: var(--hairline); }
.mode-button::before {
  content: "";
  position: absolute;
  inset: -1px auto -1px 0;
  width: 4px;
  background: transparent;
}
.mode-button:hover { background: var(--sheet); }
.mode-button:hover::before { background: var(--rule); }
.mode-button[aria-pressed="true"] { background: var(--ink); color: var(--paper); }
.mode-button[aria-pressed="true"]::before { background: var(--ruling); }
.mode-button:focus-visible { z-index: 1; border-radius: 0; }

.mode-number {
  grid-row: 1 / span 2;
  font-family: var(--font-mono);
  font-size: var(--step-3);
  font-weight: 700;
  line-height: 1;
  align-self: center;
}
.mode-name { font-size: var(--step-0); font-weight: 650; line-height: 1.25; }
.mode-sensor { font-family: var(--font-mono); font-size: var(--step--2); line-height: 1.4; color: var(--ink-3); }
.mode-button[aria-pressed="true"] .mode-sensor { color: inherit; opacity: .78; }

.mode-gap {
  display: grid;
  grid-template-columns: 32px minmax(0, 1fr);
  column-gap: var(--s-2);
  align-items: baseline;
  padding: var(--s-2) var(--s-3) var(--s-2) var(--s-4);
  border-bottom: var(--hairline);
  color: var(--ink-3);
  background-image: repeating-linear-gradient(-45deg, transparent 0 5px, var(--grid-minor) 5px 6px);
}
.mode-gap span:first-child { font-family: var(--font-mono); font-size: var(--step--1); font-weight: 700; }
.mode-gap span:last-child { font-size: var(--step--1); }

.sheet {
  min-width: 0;
  padding: var(--s-5) 0 var(--s-6) var(--s-6);
}

.sheet-head {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: var(--s-2) var(--s-5);
  align-items: start;
}
.sheet-head h2 {
  font-size: var(--step-4);
  font-weight: 750;
  line-height: var(--leading-tight);
  letter-spacing: -.022em;
  overflow-wrap: anywhere;
}
.sheet-head .kicker { margin-bottom: var(--s-2); }
.kicker .sep { margin-inline: .5ch; color: var(--rule); }
#experiment-description {
  grid-column: 1;
  max-width: var(--measure);
  margin-top: var(--s-2);
  color: var(--ink-2);
  text-wrap: pretty;
}

/* One clear statement that nothing here is live. */
.simulation-status {
  grid-column: 2;
  grid-row: 1 / span 3;
  padding: var(--s-1) var(--s-2);
  border: 2px solid var(--ruling);
  color: var(--ruling);
  font-family: var(--font-mono);
  font-size: var(--step--2);
  font-weight: 700;
  letter-spacing: .06em;
  line-height: 1.35;
  text-align: center;
  text-transform: uppercase;
  white-space: nowrap;
}

/* Readouts: large, mono, legible from the back row. */
.readout-strip { margin-top: var(--s-6); }
.readout-strip .label { display: block; margin-bottom: var(--s-2); }
.readouts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(188px, 1fr));
  border-top: var(--hairline);
}
.readout {
  min-width: 0;
  padding: var(--s-3) var(--s-4) var(--s-3) 0;
  border-bottom: var(--hairline);
}
.readout-label {
  display: flex;
  align-items: center;
  gap: var(--s-2);
  font-family: var(--font-mono);
  font-size: var(--step--1);
  color: var(--ink-2);
}
.pen-swatch { width: 20px; height: 3px; flex: none; background: var(--series-color); }
.readout output {
  display: block;
  margin-top: var(--s-1);
  font-size: var(--step-readout);
  font-weight: 650;
  line-height: 1.05;
  letter-spacing: -.02em;
  white-space: nowrap;
}
.readouts[data-count="4"] output { font-size: clamp(1.625rem, 1rem + 1.5vw, 2.375rem); }
.readout .unit { font-size: .5em; font-weight: 500; letter-spacing: 0; color: var(--ink-2); }

/* The plot */
.chart-shell { margin-top: var(--s-5); }
#chart {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 920 / 340;
  background: var(--sheet);
  border: 1px solid var(--grid-major);
  overflow: visible;
}
.grid-line { stroke: var(--grid-minor); stroke-width: 1; shape-rendering: crispEdges; }
.grid-line--major { stroke: var(--grid-major); }
.axis-label { fill: var(--ink-3); font-family: var(--font-mono); font-size: 11px; font-variant-numeric: tabular-nums; }
.series-line { fill: none; stroke-width: 2.25; stroke-linecap: round; stroke-linejoin: round; }
.pen-head { stroke-width: 2; fill: var(--sheet); }
.playhead { stroke: var(--ruling); stroke-width: 1; stroke-dasharray: 2 3; }

.chart-shell figcaption {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--s-2) var(--s-5);
  margin-top: var(--s-3);
}
.caption-title { font-family: var(--font-mono); font-size: var(--step--2); color: var(--ink-3); }
.caption-title strong { color: var(--ink); font-weight: 700; }
.legend { display: flex; flex-wrap: wrap; gap: var(--s-1) var(--s-5); }
.legend-item {
  display: inline-flex;
  align-items: center;
  gap: var(--s-2);
  font-family: var(--font-mono);
  font-size: var(--step--2);
  color: var(--ink-2);
}

/* Playback controls */
.simulation-controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--s-3);
  margin-top: var(--s-5);
}
.simulation-controls button {
  min-height: 44px;
  padding: 0 var(--s-4) 0 var(--s-3);
  border: 2px solid var(--ink);
  border-radius: var(--radius);
  background: var(--ink);
  color: var(--paper);
  display: inline-flex;
  align-items: center;
  gap: var(--s-2);
  font-size: var(--step--1);
  font-weight: 700;
  line-height: 1;
  cursor: pointer;
  transition: background-color var(--duration-quick) var(--ease-out), color var(--duration-quick) var(--ease-out), border-color var(--duration-quick) var(--ease-out);
}
.simulation-controls button:hover { background: var(--ink-2); border-color: var(--ink-2); }
.simulation-controls button:active { transform: translateY(1px); }
.simulation-controls button.secondary { background: var(--paper); color: var(--ink); border-color: var(--ink-3); }
.simulation-controls button.secondary:hover { background: var(--sheet); border-color: var(--ink); }
.simulation-controls svg { width: 18px; height: 18px; fill: currentColor; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
#reset-fixture svg { fill: none; }

#stream-status {
  display: inline-flex;
  align-items: center;
  gap: var(--s-2);
  margin-left: var(--s-2);
  font-family: var(--font-mono);
  font-size: var(--step--2);
  color: var(--ink-2);
}
#stream-status::before {
  content: "";
  width: 8px;
  height: 8px;
  flex: none;
  border: 1.5px solid var(--ink-3);
  border-radius: 50%;
}
#stream-status[data-state="running"]::before { background: var(--ruling); border-color: var(--ruling); }
.controls-note { flex-basis: 100%; max-width: var(--measure); color: var(--ink-3); font-size: var(--step--1); }

/* The 20-byte frame */
.frame {
  margin-top: var(--s-7);
  padding-top: var(--s-4);
  border-top: 2px solid var(--ink);
}
.frame-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--s-2) var(--s-5);
}
.frame-head h3 { font-size: var(--step-1); font-weight: 700; }
.frame-fields {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 0 var(--s-2);
  margin-top: var(--s-4);
}
.frame-field {
  display: grid;
  grid-template-rows: auto auto auto auto;
  min-width: 0;
  --series-color: var(--ink-3);
}
.frame-field .field-meta { display: flex; justify-content: space-between; gap: var(--s-2); }
.field-channel { font-family: var(--font-mono); font-size: var(--step--1); font-weight: 700; }
.frame-bytes {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  margin-top: var(--s-2);
  border-top: 3px solid var(--series-color);
  background: var(--sheet);
  font-family: var(--font-mono);
  font-size: var(--step--1);
  font-variant-numeric: tabular-nums;
  text-align: center;
}
.frame-bytes span { padding: var(--s-2) 0; border-right: var(--hairline); border-bottom: var(--hairline); }
.frame-bytes span:first-child { border-left: var(--hairline); }
.frame-field[data-empty] .frame-bytes { border-top-style: dashed; color: var(--ink-3); }
.field-value {
  margin-top: var(--s-2);
  font-family: var(--font-mono);
  font-size: var(--step-0);
  font-weight: 650;
  font-variant-numeric: tabular-nums;
  overflow-wrap: anywhere;
}
.field-meaning { font-size: var(--step--1); color: var(--ink-2); }
.frame-field[data-empty] .field-value,
.frame-field[data-empty] .field-meaning { color: var(--ink-3); }
.frame-note { max-width: var(--measure); margin-top: var(--s-4); color: var(--ink-2); font-size: var(--step--1); text-wrap: pretty; }

/* ---------- Signal path ---------- */

.section { padding-block: var(--s-9) 0; }
.section-head { display: grid; gap: var(--s-2); margin-bottom: var(--s-6); }
.section-head h2 {
  font-size: var(--step-3);
  font-weight: 750;
  line-height: 1.15;
  letter-spacing: -.018em;
}

.signal-path {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--s-6);
  counter-reset: station;
}
.station {
  position: relative;
  padding-top: var(--s-6);
  border-top: 2px solid var(--ink);
}
.station::before {
  content: "";
  position: absolute;
  top: -7px;
  left: 0;
  width: 12px;
  height: 12px;
  border: 2px solid var(--ink);
  border-radius: 50%;
  background: var(--paper);
}
.station:last-child::before { background: var(--ruling); border-color: var(--ruling); }
.station .label { position: absolute; top: var(--s-2); left: 0; }
.station h3 { font-size: var(--step-2); font-weight: 700; line-height: 1.2; letter-spacing: -.01em; }
.station p { margin-top: var(--s-2); color: var(--ink-2); text-wrap: pretty; }
.station code { overflow-wrap: break-word; }
.station-fact {
  display: block;
  margin-top: var(--s-4);
  padding: var(--s-2) var(--s-3);
  border-left: 3px solid var(--grid-major);
  background: var(--sheet);
  font-family: var(--font-mono);
  font-size: var(--step--1);
  overflow-wrap: break-word;
}
.station-fact a { font-weight: 700; }

/* ---------- Scope ledger ---------- */

.ledger {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  border-top: 2px solid var(--ink);
}
.ledger section { padding: var(--s-4) var(--s-5) var(--s-5) 0; }
.ledger section + section { padding-left: var(--s-5); border-left: var(--hairline); }
.ledger h3 { margin-bottom: var(--s-3); font-size: var(--step-0); font-weight: 700; }
.ledger li {
  position: relative;
  padding: var(--s-2) 0 var(--s-2) var(--s-5);
  border-top: var(--hairline);
  color: var(--ink-2);
  font-size: var(--step--1);
}
.ledger li::before {
  position: absolute;
  left: 0;
  font-family: var(--font-mono);
  font-weight: 700;
  color: var(--ink);
}
.ledger-real li::before { content: "="; }
.ledger-sim li::before { content: "≈"; color: var(--ruling); }
.ledger-check li::before { content: "!"; }

.aside-note {
  max-width: var(--measure);
  margin-top: var(--s-6);
  color: var(--ink-2);
  font-size: var(--step--1);
}

/* ---------- Footer ---------- */

.colophon {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--s-3) var(--s-6);
  margin-top: var(--s-9);
  padding-block: var(--s-5) var(--s-6);
  border-top: var(--hairline);
  color: var(--ink-3);
  font-size: var(--step--1);
}
.colophon nav { display: flex; flex-wrap: wrap; gap: var(--s-2) var(--s-5); }
.colophon a { color: var(--ink-2); }

/* ---------- Tablet ---------- */

@media (max-width: 1080px) {
  :root { --index-width: 216px; }
  .statement { grid-template-columns: 1fr; padding-block: var(--s-7) var(--s-6); }
  .spec { grid-template-columns: repeat(4, auto); justify-content: start; column-gap: var(--s-6); }
  .spec div { display: grid; gap: var(--s-1); }
  .frame-fields { grid-template-columns: repeat(5, minmax(0, 1fr)); }
  .field-meaning { font-size: var(--step--2); }
}

@media (max-width: 860px) {
  .recorder { grid-template-columns: 1fr; }
  .mode-index { padding: var(--s-4) 0; border-right: 0; }
  .mode-list {
    grid-template-columns: repeat(6, minmax(0, 1fr)) minmax(0, 1fr);
    gap: var(--s-1);
  }
  .mode-button,
  .mode-button:first-child {
    min-height: 64px;
    padding: var(--s-2) var(--s-1);
    border: var(--edge);
    border-radius: var(--radius);
    grid-template-columns: 1fr;
    justify-items: center;
    text-align: center;
  }
  .mode-button::before { inset: auto 0 -1px 0; width: auto; height: 4px; }
  .mode-number { grid-row: auto; font-size: var(--step-2); }
  .mode-name { font-size: var(--step--2); font-weight: 600; line-height: 1.2; margin-top: var(--s-1); }
  .mode-sensor { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; }
  .mode-button[aria-pressed="true"] { border-color: var(--ink); }
  .mode-gap {
    grid-column: 1 / -1;
    grid-row: 2;
    display: block;
    padding: var(--s-2) 0 0;
    border: 0;
    background: none;
    font-size: var(--step--2);
  }
  .mode-gap span:first-child { display: none; }
  .mode-gap span:last-child { font-family: var(--font-mono); font-size: var(--step--2); }
  .sheet { padding: var(--s-4) 0 var(--s-5); border-top: var(--hairline); }
  .signal-path { grid-template-columns: 1fr; gap: 0; }
  .station { padding: var(--s-6) 0 var(--s-6) var(--s-6); border-top: 0; border-left: 2px solid var(--ink); }
  .station:last-child { padding-bottom: 0; }
  .station::before { top: 0; left: -7px; }
  .station .label { top: 0; left: var(--s-6); transform: translateY(-1px); }
  .station h3 { margin-top: var(--s-1); }
  .ledger { grid-template-columns: 1fr; }
  .ledger section, .ledger section + section { padding: var(--s-4) 0 var(--s-5); border-left: 0; }
  .ledger section + section { border-top: var(--hairline); }
}

/* ---------- Phone: its own layout, not a squeezed desktop ---------- */

@media (max-width: 600px) {
  .masthead { flex-wrap: wrap; row-gap: var(--s-2); padding-block: var(--s-3); }
  .masthead nav { gap: var(--s-4); }
  .statement { padding-block: var(--s-5); }
  .statement-lede { font-size: var(--step-0); }
  /* The spec plate repeats the frame panel and step 02; on a phone the plot matters more. */
  .spec { display: none; }
  /* Visually hidden, still part of each key's accessible name. */
  .mode-name { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; }
  .mode-index h2 { margin-bottom: var(--s-2); }
  .mode-button, .mode-button:first-child { min-height: 52px; }
  .sheet-head { grid-template-columns: 1fr; }
  .simulation-status { grid-column: 1; grid-row: auto; justify-self: start; margin-top: var(--s-2); }
  #chart { aspect-ratio: 4 / 3.4; }
  .readout-strip { margin-top: var(--s-5); }
  .readouts { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .readout { padding-right: var(--s-2); }
  .readout:nth-child(even) { padding-left: var(--s-3); border-left: var(--hairline); }
  .readout:only-child { grid-column: 1 / -1; }
  .simulation-controls button { flex: 1 1 100%; justify-content: center; }
  #stream-status { margin-left: 0; }
  .frame-fields { grid-template-columns: 1fr; gap: 0; }
  .frame-field {
    grid-template-columns: 5.5em minmax(0, 1fr);
    grid-template-rows: auto auto auto;
    column-gap: var(--s-3);
    padding-block: var(--s-3);
    border-bottom: var(--hairline);
  }
  .frame-field .field-meta { grid-column: 1; grid-row: 1 / span 3; flex-direction: column; justify-content: start; gap: 0; }
  .frame-bytes, .field-value, .field-meaning { grid-column: 2; }
  .frame-bytes { margin-top: 0; }
  .field-value { margin-top: var(--s-1); }
  .section { padding-top: var(--s-8); }
}

/* ---------- Dark: the night sheet ---------- */

@media (prefers-color-scheme: dark) {
  .mode-button[aria-pressed="true"] .mode-sensor { opacity: .82; }
  .station:last-child::before { border-color: var(--ruling); }
}

/* ---------- Forced colours: state must not rely on background alone ---------- */

@media (forced-colors: active) {
  .mode-button[aria-pressed="true"] { outline: 3px solid Highlight; outline-offset: -3px; }
  #stream-status::before, .pen-swatch { forced-color-adjust: none; }
}

/* ---------- Motion and print ---------- */

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition-duration: 0s !important; }
}

@media print {
  :root { --paper: #fff; --sheet: #fff; }
  .masthead nav, .skip-link, .simulation-controls, .mode-index { display: none; }
  .recorder { grid-template-columns: 1fr; }
  .sheet { padding-left: 0; }
  .section { padding-top: var(--s-6); break-inside: avoid; }
}