:root {
  color-scheme: light;

  /* Signage type is set condensed; Hanzi falls through to PingFang and stays
     upright, which is how bilingual metro signage is actually set. */
  --font-sign: "Helvetica Neue", Helvetica, "Arial Narrow", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-text: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-data: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Monaco, Consolas, monospace;

  /* Kept as aliases so the docs stylesheet keeps resolving. */
  --font-display: var(--font-sign);
  --font-mono: var(--font-data);

  /* Ink is blue-black, the color of enamel station signage — not neutral grey. */
  --ink: #12161c;
  --ink-panel: #1a212a;
  --ink-raised: #222b36;

  /* Cool platform grey. Deliberately not cream. */
  --paper: #e7eaec;
  --paper-deep: #dbe0e3;
  --white: #ffffff;

  /* The app icon's own orange, sampled from assets/justgo-icon.png. */
  --signal: #e58224;
  --accent: #9a5410;        /* text-safe orange on light grounds */
  --accent-strong: #7d430b;
  --accent-on-dark: #f2a04a;
  --accent-soft: #f7ece1;

  --slate: #545d68;
  --slate-soft: #8b949e;
  --slate-on-dark: #9aa5b1;

  --rule: #c6ccd1;
  --rule-soft: #d6dbdf;
  --rule-on-dark: rgba(255, 255, 255, 0.15);

  /* Line colors encode a real metro line and are used nowhere else. */
  --line-1: #c8382e;
  --line-2: #1c63a8;

  /* Aliases the docs stylesheet still references. */
  --parchment: var(--paper);
  --pearl: #f2f4f5;
  --tile-1: var(--ink);
  --tile-2: var(--ink-panel);
  --tile-3: var(--ink);
  --hairline: var(--rule);
  --divider: var(--rule-soft);
  --muted: var(--slate);
  --canvas: var(--paper);

  --content: 72rem;
  --measure: 64ch;
  --gutter: clamp(1.25rem, 4vw, 2.5rem);

  --step: 0.35s;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 7rem;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: var(--font-text);
  font-size: 17px;
  font-weight: 400;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

img {
  height: auto;
}

a {
  color: inherit;
  text-decoration: none;
}

button,
input,
select,
textarea {
  font: inherit;
}

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

/* Signage voice: condensed grotesque, uppercase, set tight. -------------- */

h1,
h2,
h3,
h4,
h5,
h6 {
  margin: 0;
  font-family: var(--font-sign);
  font-stretch: condensed;
  font-weight: 700;
  line-height: 0.96;
  letter-spacing: -0.005em;
  text-transform: uppercase;
}

p,
blockquote,
figure,
dl {
  margin-top: 0;
}

p {
  text-wrap: pretty;
}

code,
kbd,
samp,
pre,
.mono {
  font-family: var(--font-data);
}

/* The utility layer: machine type. Every label, count and timestamp. ------ */

.label {
  display: block;
  margin: 0;
  color: var(--slate);
  font-family: var(--font-data);
  font-size: 11px;
  font-weight: 500;
  line-height: 1.2;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

/* Ink on the light grounds; dark sections override to the signal orange. */
:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 3px;
}

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

.wrap {
  width: min(var(--content), calc(100% - (var(--gutter) * 2)));
  margin-inline: auto;
}

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

.skip-link {
  position: fixed;
  z-index: 1000;
  top: 0.5rem;
  left: 0.5rem;
  padding: 0.65rem 1rem;
  color: var(--ink);
  background: var(--signal);
  font-family: var(--font-data);
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  transform: translateY(-200%);
  transition: transform 160ms ease;
}

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

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    /* Without this, a staggered `backwards` fill keeps elements hidden for the
       length of their delay even though the animation itself is neutralised. */
    animation-delay: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}