/* SPDX-License-Identifier: Apache-2.0 */
/*
 * Aoshingo website styles: "night crossing".
 *
 * Every page opens with a night-blue band (the app icon's colours) that holds the header and one
 * large heading, and ends in a zebra crossing. Below it, content sits on rounded tiles: one idea per
 * tile, at most a line or two of text, details on the sub-pages. Type sizes step down clearly
 * (display > h1 > h2 > h3 > body > small).
 *
 * No web fonts and nothing loaded from outside the site except the GitHub and Cloudflare
 * infrastructure allowed in scripts/check-pages.mjs (see docs/website.md). Colours meet WCAG 2.2 AA
 * in light, dark and increased-contrast modes; the signal colours are the ones the iOS app uses
 * (App/Views/Signal/SignalAppearance.swift).
 */

:root {
  color-scheme: light dark;

  /* Page */
  --bg: #f2f4f8;
  --tile: #ffffff;
  --tile-soft: #e9edf4;
  --text: #0c1424;
  --muted: #4b566a;
  --line: #d9dfe9;
  --line-strong: #6a7588;
  --accent: #00705e;
  --accent-hover: #00574a;
  --accent-ink: #ffffff;
  --accent-soft: #dff1ec;
  --focus: #1d4ed8;
  --code-bg: #e9edf4;
  --step-bg: #0a1a3a;
  --step-fg: #ffffff;
  --night-tile-edge: transparent;

  /* The night band. The same in light and dark mode. */
  --night: #0a1a3a;
  --night-glow: #1b4b8c;
  --night-tile: #0e2147;
  --on-night: #ffffff;
  --on-night-muted: #c5d0e2;
  --on-night-accent: #4be3c1;
  --on-night-focus: #ffd34d;
  --zebra: #e9eef6;

  /* Road sign yellow, for the safety notes. The same in light and dark mode. */
  --sign: #ffd23f;
  --sign-ink: #1c1600;

  /* Signal colours, as in SignalAppearance.swift. */
  --sig-green: #00806b;
  --sig-red: #d7261e;
  --sig-cud-blue: #005aff;
  --sig-cud-red: #ff4b00;
  --sig-neutral: #d5dbe4;
  --sig-neutral-text: #0c1424;

  --radius: 1rem;
  --radius-lg: 1.75rem;
  --wrap: 70rem;
  --measure: 40rem;

  --fs-display: clamp(2.375rem, 1.3rem + 4.6vw, 4.5rem);
  --fs-h1: clamp(2.125rem, 1.5rem + 2.8vw, 3.5rem);
  --fs-h2: clamp(1.625rem, 1.25rem + 1.7vw, 2.625rem);
  --fs-h3: 1.25rem;
  --fs-lead: clamp(1.0625rem, 1rem + 0.35vw, 1.25rem);
  --fs-small: 0.875rem;

  --space-section: clamp(4rem, 2.75rem + 5vw, 7rem);

  --font: system-ui, -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Hiragino Kaku Gothic ProN",
    "Noto Sans JP", "Yu Gothic UI", "Yu Gothic", Meiryo, "Segoe UI", Roboto, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #070e1c;
    --tile: #111b2e;
    --tile-soft: #18243b;
    --text: #e9eef6;
    --muted: #aab5c7;
    --line: #26334b;
    --line-strong: #8693a8;
    --accent: #5fd8bf;
    --accent-hover: #98e8d7;
    --accent-ink: #03201a;
    --accent-soft: #123129;
    --focus: #ffd34d;
    --code-bg: #18243b;
    --step-bg: var(--accent);
    --step-fg: var(--accent-ink);
    --night-tile-edge: #22345a;

    --sig-neutral: #364156;
    --sig-neutral-text: #f3f5f8;
  }
}

@media (prefers-contrast: more) {
  :root {
    --muted: var(--text);
    --line: var(--line-strong);
    --on-night-muted: #ffffff;
  }
}

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

/* Keep the hidden attribute working on elements that set their own display (such as .button). */
[hidden] {
  display: none !important;
}

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-padding-top: 1.5rem;
}

/* Follow the iOS text size setting (Dynamic Type) in Safari on iPhone and iPad only. */
@supports (font: -apple-system-body) and (-webkit-touch-callout: none) {
  html {
    font: -apple-system-body;
  }
}

@media (prefers-reduced-motion: no-preference) {
  html {
    scroll-behavior: smooth;
  }
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 1.0625rem;
  line-height: 1.8;
  line-break: strict;
  overflow-wrap: anywhere;
  word-break: normal;
  -webkit-font-smoothing: antialiased;
}

/* Break Japanese lines between phrases, not inside words (Chromium 119+; others ignore it). */
body:lang(ja) {
  word-break: auto-phrase;
}

p,
li,
dd {
  text-wrap: pretty;
}

h1,
h2,
h3 {
  line-height: 1.3;
  text-wrap: balance;
  font-feature-settings: "palt";
  letter-spacing: 0.01em;
}

h1 {
  font-size: var(--fs-h1);
  font-weight: 800;
  margin: 0 0 1rem;
}

h2 {
  font-size: var(--fs-h2);
  font-weight: 800;
  margin: 0 0 1.5rem;
}

h3 {
  font-size: var(--fs-h3);
  font-weight: 700;
  margin: 2.5rem 0 0.5rem;
}

p,
ul,
ol,
dl,
table,
figure {
  margin: 0 0 1.25rem;
}

ul,
ol {
  padding-inline-start: 1.5em;
}

li + li {
  margin-top: 0.4em;
}

img,
svg {
  max-width: 100%;
}

a {
  color: var(--accent);
  text-decoration-thickness: 0.08em;
  text-underline-offset: 0.22em;
}

a:hover {
  color: var(--accent-hover);
  text-decoration-thickness: 0.14em;
}

:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 3px;
  border-radius: 4px;
}

code,
kbd {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background: var(--code-bg);
  padding: 0.1em 0.35em;
  border-radius: 0.3em;
}

strong {
  font-weight: 700;
}

.sprite {
  position: absolute;
  width: 0;
  height: 0;
  overflow: hidden;
}

.visually-hidden {
  position: absolute !important;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: -10rem;
  z-index: 10;
  padding: 0.75rem 1rem;
  background: var(--on-night);
  color: var(--night);
  border: 2px solid var(--night);
  border-radius: 0.5rem;
  font-weight: 700;
}

.skip-link:focus {
  top: 1rem;
}

/* ---------- Layout ---------- */

.wrap {
  width: min(100% - 2.5rem, var(--wrap));
  margin-inline: auto;
}

.narrow {
  max-width: var(--measure);
}

.center {
  text-align: center;
}

.center .narrow {
  margin-inline: auto;
}

.section {
  padding-block: var(--space-section);
}

.section + .section {
  padding-top: 0;
}

/* Small label above a heading. */
.eyebrow {
  margin: 0 0 0.75rem;
  color: var(--accent);
  font-size: var(--fs-small);
  font-weight: 800;
  letter-spacing: 0.1em;
}

.lead {
  font-size: var(--fs-lead);
  color: var(--muted);
  line-height: 1.75;
}

/* ---------- The night band: header and page heading ---------- */

.night {
  --text: var(--on-night);
  --muted: var(--on-night-muted);
  --accent: var(--on-night-accent);
  --accent-hover: #9af2dd;
  --focus: var(--on-night-focus);
  background: var(--night);
  color: var(--on-night);
}

.site-header {
  background: var(--night);
}

.header-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.25rem 1.5rem;
  min-height: 4.5rem;
  padding-block: 0.5rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.65rem;
  color: var(--on-night);
  font-weight: 800;
  font-size: 1.125rem;
  text-decoration: none;
  letter-spacing: 0.01em;
}

.brand:hover {
  color: var(--on-night);
}

.brand img {
  width: 2rem;
  height: 2rem;
  border-radius: 0.55rem;
  box-shadow: 0 0 0 1px rgb(255 255 255 / 0.18);
}

.site-nav ul {
  display: flex;
  flex-wrap: wrap;
  gap: 0 0.25rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.site-nav li + li {
  margin: 0;
}

.site-nav a {
  display: block;
  padding: 0.5rem 0.8rem;
  border-radius: 999px;
  color: var(--on-night-muted);
  font-size: 0.9375rem;
  font-weight: 700;
  text-decoration: none;
  line-height: 1.5;
}

.site-nav a:hover,
.site-nav a[aria-current="page"] {
  color: var(--on-night);
  background: rgb(255 255 255 / 0.12);
}

/* The glow sits low and to the right, so the band joins the header without a seam. */
.hero,
.page-hero {
  position: relative;
  overflow: hidden;
  background:
    radial-gradient(42rem 30rem at 82% 62%, var(--night-glow) 0%, rgb(27 75 140 / 0) 70%),
    var(--night);
}

/* Zebra crossing along the bottom edge of the band. */
.zebra {
  height: 2.5rem;
  background: repeating-linear-gradient(90deg, var(--zebra) 0 3.5rem, transparent 3.5rem 7rem);
  background-position: center;
}

.page-hero .zebra {
  height: 1.75rem;
}

/* ---------- Buttons ---------- */

.actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem 1rem;
  list-style: none;
  padding: 0;
  margin: 0;
}

.center .actions {
  justify-content: center;
}

.actions li + li {
  margin: 0;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 3.25rem;
  padding: 0.5rem 1.75rem;
  border-radius: 0.9rem;
  border: 2px solid transparent;
  font: inherit;
  font-size: 1rem;
  font-weight: 800;
  line-height: 1.4;
  text-decoration: none;
  cursor: pointer;
}

.button-primary {
  background: var(--accent);
  color: var(--accent-ink);
}

.button-primary:hover {
  background: var(--accent-hover);
  color: var(--accent-ink);
}

.button-secondary {
  background: transparent;
  color: var(--accent);
  border-color: var(--accent);
}

.button-secondary:hover {
  background: var(--accent-soft);
  color: var(--accent-hover);
}

/* On the night band and night tiles. */
.button-light {
  background: var(--on-night);
  color: var(--night);
}

.button-light:hover {
  background: #dfe7f3;
  color: var(--night);
}

.button-outline-light {
  color: var(--on-night);
  border-color: rgb(255 255 255 / 0.7);
}

.button-outline-light:hover {
  color: var(--on-night);
  background: rgb(255 255 255 / 0.1);
  border-color: var(--on-night);
}

.button[aria-disabled="true"] {
  opacity: 0.6;
  cursor: progress;
}

/* A quiet link with an arrow, for "read more". */
.more {
  font-weight: 800;
  text-decoration: none;
}

.more::after {
  content: "→";
  display: inline-block;
  margin-inline-start: 0.35em;
}

.more:hover {
  text-decoration: underline;
}

.more-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 2rem;
  list-style: none;
  padding: 0;
  margin: 2rem 0 0;
}

.more-links li + li {
  margin: 0;
}

/* ---------- Top page: hero ---------- */

.hero-grid {
  display: grid;
  align-items: center;
  gap: 3rem 2.5rem;
  padding-block: clamp(2.5rem, 1.5rem + 4vw, 5rem) clamp(4rem, 3rem + 4vw, 7rem);
}

@media (min-width: 52rem) {
  .hero-grid {
    grid-template-columns: minmax(0, 1.25fr) minmax(0, 0.75fr);
  }
}

.status-pill {
  display: inline-flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0 0.5em;
  margin: 0 0 1.75rem;
  padding: 0.3rem 1rem 0.3rem 0.8rem;
  border-radius: 999px;
  background: rgb(255 255 255 / 0.1);
  color: var(--on-night-muted);
  font-size: var(--fs-small);
  font-weight: 700;
  line-height: 1.6;
}

.status-pill::before {
  content: "";
  flex: none;
  width: 0.55rem;
  height: 0.55rem;
  border-radius: 50%;
  background: var(--sign);
}

.status-pill strong {
  color: var(--on-night);
}

.hero h1 {
  font-size: var(--fs-display);
  line-height: 1.15;
  letter-spacing: -0.01em;
  margin-bottom: 1.5rem;
}

.hero h1 em {
  font-style: normal;
  color: var(--on-night-accent);
}

.hero .lead {
  max-width: 30em;
  margin: 0 0 2.25rem;
}

/* A pedestrian signal head: red (off) above, green (on) below, as in Japan. */
.lamp {
  position: relative;
  justify-self: center;
  width: min(15rem, 62vw);
  margin: 0;
  padding: 1.4rem;
  border-radius: 2.5rem;
  background: #081226;
  box-shadow:
    inset 0 0 0 2px #22345a,
    0 2.5rem 5rem -2rem #000000;
}

.lamp-light {
  display: grid;
  place-items: center;
  aspect-ratio: 1;
  border-radius: 1.6rem;
}

.lamp-light + .lamp-light {
  margin-top: 1.1rem;
}

.lamp-light svg {
  width: 64%;
  height: 64%;
}

.lamp-off {
  background: #3a1517;
  color: #5c2326;
}

.lamp-on {
  background: var(--sig-green);
  color: #ffffff;
  box-shadow: 0 0 3.5rem 0.4rem rgb(75 227 193 / 0.45);
}

.lamp-waves {
  position: absolute;
  top: 1.5rem;
  right: -3.25rem;
  width: 4.5rem;
  height: 4.5rem;
  color: var(--on-night-accent);
}

/* ---------- Tiles ---------- */

.tile {
  padding: clamp(1.5rem, 1.2rem + 1vw, 2rem);
  border-radius: var(--radius-lg);
  background: var(--tile);
}

.tile > :last-child {
  margin-bottom: 0;
}

.tile-green {
  --text: #ffffff;
  --muted: #ffffff;
  background: var(--sig-green);
  color: #ffffff;
}

.tile-night {
  --text: var(--on-night);
  --muted: var(--on-night-muted);
  --accent: var(--on-night-accent);
  --accent-hover: #9af2dd;
  --focus: var(--on-night-focus);
  background: var(--night);
  color: var(--on-night);
  box-shadow: inset 0 0 0 1px var(--night-tile-edge);
}

/* Top page: tiles of different sizes, one fact each. */
.bento {
  display: grid;
  grid-template-columns: repeat(6, minmax(0, 1fr));
  gap: 1rem;
  list-style: none;
  padding: 0;
  margin: 0;
}

.bento > li {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 1.5rem;
  min-height: 14rem;
  margin: 0;
  grid-column: span 2;
}

.bento > .wide {
  grid-column: span 3;
}

.bento h3 {
  margin: 0 0 0.2rem;
  font-size: 1.3125rem;
}

.bento p {
  margin: 0;
  color: var(--muted);
  font-size: 0.9375rem;
  line-height: 1.7;
}

.bento .big {
  margin: 0;
  color: var(--text);
  font-size: clamp(4rem, 3rem + 3vw, 5.5rem);
  font-weight: 800;
  line-height: 1;
  letter-spacing: -0.03em;
  font-feature-settings: "palt";
}

.big small {
  font-size: 0.3em;
  letter-spacing: 0;
  margin-inline: 0.15em;
}

.bento .tile-icon {
  width: 3.5rem;
  height: 3.5rem;
  color: var(--accent);
}

.speech {
  align-self: flex-start;
  margin: 0;
  padding: 0.8rem 1.1rem;
  border-radius: 1.1rem 1.1rem 1.1rem 0.3rem;
  background: var(--tile-soft);
  color: var(--text);
  font-weight: 800;
}

.bento .speech {
  color: var(--text);
  font-size: 1.0625rem;
}

.swatches {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
}

.swatches .swatch {
  display: grid;
  place-items: center;
  width: 3.5rem;
  height: 3.5rem;
  min-width: 0;
  padding: 0;
  border-radius: 0.9rem;
}

.swatches .swatch-cud {
  --slot-bg: var(--sig-cud-blue);
  --slot-fg: #ffffff;
}

.swatches .swatch-mono {
  --slot-bg: #ffffff;
  --slot-fg: #000000;
  border: 2px solid #000000;
}

.swatches .swatch svg {
  width: 2rem;
  height: 2rem;
}

@media (max-width: 48rem) {
  .bento {
    grid-template-columns: minmax(0, 1fr);
  }

  .bento > li,
  .bento > .wide {
    grid-column: auto;
    min-height: 0;
  }
}

/* ---------- Signal samples (the app's look) ---------- */

.chip {
  --slot-bg: var(--sig-neutral);
  --slot-fg: var(--sig-neutral-text);
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.1rem;
  min-width: 4.5rem;
  padding: 0.6rem 0.5rem 0.5rem;
  border-radius: 0.9rem;
  background: var(--slot-bg);
  color: var(--slot-fg);
  border: 1.5px solid color-mix(in srgb, var(--slot-fg) 30%, transparent);
  font-size: 0.875rem;
  font-weight: 800;
  line-height: 1.3;
  text-align: center;
}

.chip svg {
  width: 2rem;
  height: 2rem;
}

.is-green {
  --slot-bg: var(--sig-green);
  --slot-fg: #ffffff;
}

.is-red {
  --slot-bg: var(--sig-red);
  --slot-fg: #ffffff;
}

.is-blink {
  outline: 0.25rem dashed var(--slot-fg);
  outline-offset: -0.5rem;
}

.mode-cud .is-green {
  --slot-bg: var(--sig-cud-blue);
  --slot-fg: #ffffff;
}

.mode-cud .is-red {
  --slot-bg: var(--sig-cud-red);
  --slot-fg: #000000;
}

.mode-mono .is-green {
  --slot-bg: #ffffff;
  --slot-fg: #000000;
}

.mode-mono .is-red {
  --slot-bg: #000000;
  --slot-fg: #ffffff;
}

/* ---------- Safety: road sign band ---------- */

.sign {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  align-items: center;
  gap: 1rem 1.5rem;
  padding: 1.75rem 2rem;
  border-radius: var(--radius-lg);
  background: var(--sign);
  color: var(--sign-ink);
  --focus: #0b3bb5;
}

@media (min-width: 48rem) {
  .sign {
    grid-template-columns: auto minmax(0, 1fr) auto;
  }
}

.sign > svg {
  width: 2.75rem;
  height: 2.75rem;
}

.sign p {
  margin: 0;
}

.sign strong {
  display: block;
  font-size: 1.375rem;
  line-height: 1.35;
}

.sign-link {
  grid-column: 1 / -1;
  justify-self: start;
  display: inline-flex;
  align-items: center;
  min-height: 3rem;
  padding: 0.5rem 1.25rem;
  border-radius: 0.8rem;
  background: var(--sign-ink);
  color: var(--sign);
  font-weight: 800;
  text-decoration: none;
  white-space: nowrap;
}

.sign-link:hover {
  color: #ffffff;
  background: #000000;
}

@media (min-width: 48rem) {
  .sign-link {
    grid-column: auto;
  }
}

/* The safety notes on the support page. */
.sign-panel {
  padding: 1.75rem 2rem 0.75rem;
  border-radius: var(--radius-lg);
  background: var(--sign);
  color: var(--sign-ink);
  --focus: #0b3bb5;
}

.sign-panel h2 {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin: 0 0 1rem;
  font-size: clamp(1.375rem, 1.2rem + 0.8vw, 1.75rem);
}

.sign-panel h2 svg {
  flex: none;
  width: 2rem;
  height: 2rem;
}

.sign-panel ul {
  padding-inline-start: 1.25em;
}

.sign-panel a {
  color: var(--sign-ink);
}

/* ---------- Top page: open source ---------- */

.oss {
  display: grid;
  align-items: center;
  gap: 1.5rem 2rem;
  padding: clamp(2rem, 1.25rem + 3vw, 4rem);
}

@media (min-width: 52rem) {
  .oss {
    grid-template-columns: minmax(0, 1fr) auto;
  }
}

.oss h2 {
  margin-bottom: 0.5rem;
}

.oss p {
  margin: 0;
  color: var(--muted);
}

/* ---------- Sub-page heading ---------- */

.page-hero-inner {
  padding-block: clamp(2.5rem, 1.75rem + 3vw, 4.5rem) clamp(3rem, 2.25rem + 3vw, 5rem);
}

.page-hero h1 {
  margin-bottom: 1rem;
}

.page-hero .lead {
  max-width: 34em;
  margin: 0;
}

.page-meta {
  margin: 1.5rem 0 0;
  color: var(--on-night-muted);
  font-size: var(--fs-small);
  line-height: 1.8;
}

/* "On this page": a row of links under the band. */
.page-toc ol {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  list-style: none;
  margin: 0;
  padding: 2rem 0 0;
}

.page-toc li + li {
  margin: 0;
}

.page-toc a {
  display: block;
  padding: 0.45rem 1rem;
  border-radius: 999px;
  background: var(--tile);
  color: var(--text);
  font-size: 0.9375rem;
  font-weight: 700;
  text-decoration: none;
  line-height: 1.5;
}

.page-toc a:hover {
  background: var(--accent-soft);
  color: var(--text);
}

/* A section of a sub-page: a heading with a short line under it, then tiles. */
.block {
  padding-top: clamp(3.5rem, 2.5rem + 3.5vw, 5.5rem);
}

.block:last-child {
  padding-bottom: clamp(4rem, 3rem + 4vw, 7rem);
}

.block-head {
  margin-bottom: 2rem;
}

.block-head h2 {
  margin-bottom: 0.5rem;
}

.block-head p {
  max-width: var(--measure);
  margin: 0;
  color: var(--muted);
}

/* ---------- Steps ---------- */

.steps {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(14rem, 1fr));
  gap: 1rem;
  list-style: none;
  padding: 0;
  margin: 0;
  counter-reset: step;
}

.steps > li {
  margin: 0;
  padding: 1.75rem;
  border-radius: var(--radius-lg);
  background: var(--tile);
  counter-increment: step;
}

.steps > li::before {
  content: counter(step);
  display: grid;
  place-items: center;
  width: 2.5rem;
  height: 2.5rem;
  margin-bottom: 1.25rem;
  border-radius: 50%;
  background: var(--step-bg);
  color: var(--step-fg);
  font-weight: 800;
  line-height: 1;
}

.steps h3 {
  margin: 0 0 0.35rem;
  font-size: 1.125rem;
}

.steps p {
  margin: 0;
  color: var(--muted);
}

/* Steps with an icon instead of a number (how it works). */
.flow > li::before {
  content: none;
}

.flow svg {
  width: 2.75rem;
  height: 2.75rem;
  margin-bottom: 1.25rem;
  color: var(--accent);
}

.tip {
  margin: 1rem 0 0;
  padding: 1.1rem 1.5rem;
  border-radius: var(--radius);
  background: var(--tile-soft);
}

/* ---------- Feature list ---------- */

.features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(17rem, 1fr));
  gap: 1rem;
  list-style: none;
  padding: 0;
  margin: 0;
}

.features > li {
  margin: 0;
  padding: 1.75rem;
  border-radius: var(--radius-lg);
  background: var(--tile);
}

.features svg {
  display: block;
  width: 2.25rem;
  height: 2.25rem;
  margin-bottom: 1rem;
  color: var(--accent);
}

.features h3 {
  margin: 0 0 0.35rem;
  font-size: 1.125rem;
}

.features p {
  margin: 0;
  color: var(--muted);
  font-size: 0.9375rem;
}

/* ---------- Legend of the signal states (guide page) ---------- */

/* Each row: a sample of the tile on the left (hidden from screen readers), then the term and meaning. */
.legend {
  --sample: 5.5rem;
  margin: 0;
  padding: 0.5rem clamp(1.25rem, 1rem + 1vw, 2rem);
}

.legend > div {
  position: relative;
  min-height: calc(4.25rem + 2.2rem);
  padding: 1.1rem 0 1.1rem calc(var(--sample) + 1.25rem);
}

.legend > div + div {
  border-top: 1px solid var(--line);
}

.legend dt {
  font-weight: 800;
}

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

.legend .chip,
.legend .text-sample {
  position: absolute;
  left: 0;
  top: 1.1rem;
  width: var(--sample);
  min-width: 0;
  min-height: 4.25rem;
}

.legend .text-sample {
  display: grid;
  place-items: center;
  border-radius: 0.9rem;
  background: var(--tile-soft);
  border: 1.5px solid var(--line);
  font-weight: 800;
  font-size: 0.875rem;
  text-align: center;
  line-height: 1.3;
}

.after-legend {
  max-width: var(--measure);
  margin: 1.5rem 0 0;
}

/* ---------- Colour modes (guide page) ---------- */

.modes {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(16rem, 1fr));
  gap: 1rem;
  list-style: none;
  padding: 0;
  margin: 0;
}

.modes > li {
  margin: 0;
  padding: 1.75rem;
  border-radius: var(--radius-lg);
  background: var(--tile);
}

.modes h3 {
  margin: 0 0 1rem;
  font-size: 1.125rem;
}

.modes ul {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  list-style: none;
  padding: 0;
  margin: 0 0 1rem;
}

.modes ul li + li {
  margin: 0;
}

.modes p {
  margin: 0;
  color: var(--muted);
  font-size: 0.9375rem;
}

/* ---------- FAQ ---------- */

.faq {
  margin: 0;
  padding: 0.25rem clamp(1.25rem, 1rem + 1vw, 2rem);
}

.faq details + details {
  border-top: 1px solid var(--line);
}

.faq summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1.25rem 0;
  font-size: 1.0625rem;
  font-weight: 800;
  line-height: 1.6;
  cursor: pointer;
  list-style: none;
}

/* The question is a heading, so it appears in the screen reader's list of headings. */
.faq summary h3 {
  margin: 0;
  font-size: inherit;
  font-weight: inherit;
  line-height: inherit;
}

.faq summary::-webkit-details-marker {
  display: none;
}

/* Plus sign that turns into a minus when open. */
.faq summary::after {
  content: "";
  flex: none;
  width: 2rem;
  height: 2rem;
  border-radius: 50%;
  background:
    linear-gradient(var(--accent), var(--accent)) center / 0.8rem 2px no-repeat,
    linear-gradient(var(--accent), var(--accent)) center / 2px 0.8rem no-repeat,
    var(--accent-soft);
}

.faq details[open] summary::after {
  background:
    linear-gradient(var(--accent), var(--accent)) center / 0.8rem 2px no-repeat,
    var(--accent-soft);
}

.faq summary:hover {
  color: var(--accent);
}

.faq .answer {
  max-width: var(--measure);
  padding: 0 0 1.5rem;
}

.faq .answer > :last-child {
  margin-bottom: 0;
}

/* ---------- Definition list ---------- */

.spec {
  margin: 0;
  padding: 0.25rem clamp(1.25rem, 1rem + 1vw, 2rem);
}

.spec > div {
  display: grid;
  gap: 0.25rem 2rem;
  padding: 1.25rem 0;
}

.spec > div + div {
  border-top: 1px solid var(--line);
}

@media (min-width: 40rem) {
  .spec > div {
    grid-template-columns: 10rem minmax(0, 1fr);
  }
}

.spec dt {
  font-weight: 800;
}

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

/* ---------- Contact ---------- */

.contact-options {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(17rem, 1fr));
  gap: 1rem;
  margin-bottom: 1rem;
}

.contact-options h3 {
  margin: 0 0 0.5rem;
}

.contact-options p {
  color: var(--muted);
}

.contact-widget {
  margin: 0 0 1rem;
  min-height: 4.0625rem;
}

.contact-status:empty {
  display: none;
}

.contact-result {
  color: var(--text);
  font-size: 1.125rem;
  font-weight: 800;
}

/* ---------- Long text (privacy policy, credits) ---------- */

.prose > :last-child,
.prose > .narrow > :last-child {
  margin-bottom: 0;
}

.prose h3 {
  margin-top: 2.25rem;
}

.doc {
  min-width: 0;
  padding: clamp(1.5rem, 1rem + 2.5vw, 3.5rem);
  border-radius: var(--radius-lg);
  background: var(--tile);
}

.doc > * {
  max-width: var(--measure);
}

.doc h2 {
  margin: 3.5rem 0 1rem;
  padding-top: 2.5rem;
  border-top: 1px solid var(--line);
  font-size: clamp(1.375rem, 1.2rem + 0.8vw, 1.75rem);
}

.doc > h2:first-child {
  margin-top: 0;
  padding-top: 0;
  border-top: 0;
}

.doc h3 {
  font-size: 1.125rem;
  margin-top: 2rem;
}

.doc-layout {
  display: grid;
  gap: 1rem;
  align-items: start;
}

@media (min-width: 64rem) {
  .doc-layout {
    grid-template-columns: 15rem minmax(0, 1fr);
    gap: 2.5rem;
  }

  .side-toc {
    position: sticky;
    top: 1.5rem;
  }
}

.side-toc {
  padding: 1.5rem;
  border-radius: var(--radius-lg);
  background: var(--tile);
}

.side-toc h2 {
  margin: 0 0 0.75rem;
  color: var(--muted);
  font-size: var(--fs-small);
  letter-spacing: 0.08em;
}

.side-toc ol {
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: 0.9375rem;
  line-height: 1.5;
}

.side-toc li + li {
  margin-top: 0.1rem;
}

.side-toc a {
  display: block;
  padding: 0.35rem 0;
  color: var(--text);
  text-decoration: none;
}

.side-toc a:hover {
  color: var(--accent);
  text-decoration: underline;
}

.table-wrap {
  max-width: 100%;
  margin: 0 0 1.5rem;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9375rem;
  line-height: 1.7;
}

caption {
  margin-bottom: 0.5rem;
  color: var(--muted);
  font-size: var(--fs-small);
  font-weight: 800;
  text-align: start;
}

th,
td {
  padding: 0.75rem 0.75rem 0.75rem 0;
  border-bottom: 1px solid var(--line);
  text-align: start;
  vertical-align: top;
}

thead th {
  border-bottom: 2px solid var(--line-strong);
  font-size: var(--fs-small);
}

tbody th {
  width: 34%;
  font-weight: 700;
}

/* Tables become stacked rows on narrow screens, so they never scroll sideways. */
@media (max-width: 40rem) {
  table,
  tbody,
  tr,
  th,
  td {
    display: block;
    width: auto;
  }

  caption {
    display: block;
  }

  thead {
    position: absolute;
    width: 1px;
    height: 1px;
    overflow: hidden;
    clip-path: inset(50%);
  }

  tr {
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--line);
  }

  th,
  td {
    padding: 0;
    border: 0;
  }

  tbody th {
    width: auto;
    margin-bottom: 0.25rem;
  }
}

.back-to-top {
  margin-top: 3rem;
  font-size: var(--fs-small);
}

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

.site-footer {
  padding-block: 3rem 4rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: var(--fs-small);
  line-height: 1.8;
}

.footer-nav ul {
  display: flex;
  flex-wrap: wrap;
  gap: 0.25rem 1.5rem;
  list-style: none;
  margin: 0 0 1.5rem;
  padding: 0;
}

.footer-nav li + li {
  margin: 0;
}

.footer-nav a {
  display: inline-block;
  padding-block: 0.25rem;
  color: var(--text);
  font-weight: 700;
  text-decoration: none;
}

.footer-nav a:hover {
  color: var(--accent);
  text-decoration: underline;
}

.site-footer p {
  margin: 0 0 0.5rem;
}

.site-footer .fine {
  font-size: 0.8125rem;
}

/* ---------- Narrow screens ---------- */

@media (max-width: 40rem) {
  .header-inner {
    padding-block: 0.75rem;
  }

  .site-nav {
    width: 100%;
    margin-inline: -0.6rem;
  }

  .site-nav a {
    padding-inline: 0.6rem;
  }

  .lamp {
    width: min(10.5rem, 50vw);
    padding: 1rem;
    border-radius: 1.9rem;
  }

  .lamp-light {
    border-radius: 1.2rem;
  }

  .zebra {
    height: 1.75rem;
    background-size: 5rem 100%;
    background-image: linear-gradient(90deg, var(--zebra) 0 2.5rem, transparent 2.5rem 5rem);
    background-repeat: repeat-x;
  }

  .legend {
    --sample: 4.5rem;
  }

  .lamp-waves {
    right: -2.5rem;
    width: 3.5rem;
    height: 3.5rem;
  }
}

/* ---------- Forced colours (Windows High Contrast) ---------- */

@media (forced-colors: active) {
  .zebra,
  .lamp-waves {
    display: none;
  }

  .tile,
  .chip,
  .swatch,
  .sign,
  .sign-panel,
  .steps > li,
  .features > li,
  .modes > li,
  .tip,
  .doc,
  .side-toc,
  .lamp,
  .lamp-light,
  .speech,
  .legend .text-sample {
    border: 1px solid CanvasText;
  }

  .button,
  .site-nav a[aria-current="page"],
  .page-toc a,
  .sign-link {
    border: 1px solid ButtonText;
  }

  .steps > li::before {
    background: CanvasText;
    color: Canvas;
    forced-color-adjust: none;
  }

  .faq summary::after {
    forced-color-adjust: none;
    background:
      linear-gradient(CanvasText, CanvasText) center / 0.8rem 2px no-repeat,
      linear-gradient(CanvasText, CanvasText) center / 2px 0.8rem no-repeat,
      Canvas;
    border: 1px solid CanvasText;
  }

  .faq details[open] summary::after {
    background:
      linear-gradient(CanvasText, CanvasText) center / 0.8rem 2px no-repeat,
      Canvas;
  }
}

@media print {
  .site-nav,
  .page-toc,
  .zebra,
  .lamp,
  .contact-email {
    display: none;
  }

  .night,
  .hero,
  .page-hero,
  .site-header,
  .tile-night,
  .tile-green {
    background: none;
    color: #000000;
  }
}