/* MobileLinkUp marketing site.
 *
 * One stylesheet, no framework, no webfonts, no JavaScript. The whole site is
 * under 30 KB, which is the only performance optimisation that reliably
 * survives contact with a phone on a bad connection.
 */

:root {
  --bg: #ffffff;
  --bg-soft: #f6f6f4;
  --surface: #ffffff;
  --border: #e3e3df;
  --border-strong: #c9c9c2;
  --border-control: #74747e;
  --fg: #16161a;
  --fg-muted: #5d5d66;
  --accent: #1d4ed8;
  --accent-fg: #ffffff;
  --ok: #17784f;

  --font: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto,
          "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;

  --measure: 34rem;
  --radius: 6px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0e0e11;
    --bg-soft: #16161a;
    --surface: #17171b;
    --border: #27272d;
    --border-strong: #3d3d45;
    --border-control: #71717d;
    --fg: #f3f3f4;
    --fg-muted: #9d9da7;
    --accent: #8ab0ff;
    --accent-fg: #0e0e11;
    --ok: #5ccb9b;
  }
}

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

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font);
  font-size: 17px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); }
a:hover { text-decoration: none; }

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

.wrap {
  max-width: 64rem;
  margin: 0 auto;
  padding: 0 1.5rem;
}

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

.skip-link {
  position: absolute;
  left: 0.75rem;
  top: -3rem;
  z-index: 10;
  padding: 0.5rem 0.875rem;
  background: var(--accent);
  color: var(--accent-fg);
  border-radius: var(--radius);
  font-size: 0.875rem;
  text-decoration: none;
  transition: top 0.1s ease-in;
}

.skip-link:focus { top: 0.75rem; }

@media (prefers-reduced-motion: reduce) {
  .skip-link { transition: none; }
}

/* --- Header --------------------------------------------------------------- */

.site-head {
  border-bottom: 1px solid var(--border);
}

.site-head-inner {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  min-height: 4rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--fg);
  text-decoration: none;
  margin-right: auto;
}

.brand svg { display: block; }

.site-nav {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  font-size: 0.9375rem;
}

.site-nav a {
  color: var(--fg-muted);
  text-decoration: none;
}

.site-nav a:hover { color: var(--fg); }

.site-nav a[aria-current="page"] { color: var(--fg); }

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

.btn {
  display: inline-block;
  padding: 0.625rem 1.125rem;
  border: 1px solid var(--border-control);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--fg);
  font: inherit;
  font-size: 0.9375rem;
  font-weight: 500;
  text-decoration: none;
  white-space: nowrap;
}

.btn:hover { border-color: var(--fg); }

.btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-fg);
}

.btn-primary:hover { opacity: 0.9; }

/* --- Sections ------------------------------------------------------------- */

section { padding: 4.5rem 0; }

.band { background: var(--bg-soft); border-block: 1px solid var(--border); }

h1, h2, h3 { letter-spacing: -0.02em; line-height: 1.2; }

h1 { font-size: 2.5rem; margin: 0 0 1.25rem; }
h2 { font-size: 1.75rem; margin: 0 0 1rem; }
h3 { font-size: 1.0625rem; margin: 0 0 0.375rem; letter-spacing: -0.01em; }

p { margin: 0 0 1.125rem; }

.lede {
  font-size: 1.1875rem;
  color: var(--fg-muted);
  max-width: var(--measure);
}

.section-intro { max-width: var(--measure); margin-bottom: 2.5rem; }
.section-intro p:last-child { margin-bottom: 0; }

/* --- Hero ----------------------------------------------------------------- */

.hero { padding: 6rem 0 5rem; }
.hero h1 { max-width: 36rem; }
.hero .lede { margin-bottom: 2rem; }

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
}

.hero-note {
  margin: 1.75rem 0 0;
  font-size: 0.875rem;
  color: var(--fg-muted);
}

/* --- Grids ---------------------------------------------------------------- */

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(16rem, 1fr));
  gap: 2.25rem 2.5rem;
}

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

.steps {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr));
  gap: 2rem 2.5rem;
  counter-reset: step;
  list-style: none;
  margin: 0;
  padding: 0;
}

.steps li { counter-increment: step; }

.steps li::before {
  content: counter(step);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 1.75rem; height: 1.75rem;
  margin-bottom: 0.75rem;
  border: 1px solid var(--border-strong);
  border-radius: 50%;
  font-size: 0.875rem;
  font-variant-numeric: tabular-nums;
  color: var(--fg-muted);
}

.steps h3 { margin-bottom: 0.25rem; }
.steps p { margin: 0; color: var(--fg-muted); font-size: 0.9375rem; }

/* --- Facts ---------------------------------------------------------------- */

.facts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(11rem, 1fr));
  gap: 1.5rem 2rem;
  margin: 0;
  padding: 0;
}

.facts div { margin: 0; }
.facts dt { font-size: 0.8125rem; color: var(--fg-muted); margin-bottom: 0.25rem; }
.facts dd { margin: 0; font-weight: 500; }

/* --- Prose ---------------------------------------------------------------- */

.prose { max-width: var(--measure); }
.prose h2 { margin-top: 3rem; }
.prose h2:first-child { margin-top: 0; }
.prose ul { padding-left: 1.25rem; margin: 0 0 1.125rem; }
.prose li { margin-bottom: 0.5rem; }
.prose code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 0.0625rem 0.25rem;
}

/* --- Status table --------------------------------------------------------- */

.status-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9375rem;
}

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

.status-table th { font-weight: 600; }
.status-table td:last-child { color: var(--fg-muted); }

.tag {
  display: inline-block;
  padding: 0.0625rem 0.5rem;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 500;
  white-space: nowrap;
  border: 1px solid var(--border-strong);
  color: var(--fg-muted);
}

.tag-live { color: var(--ok); border-color: currentColor; }

/* --- CTA ------------------------------------------------------------------ */

.cta { text-align: center; }
.cta h2 { margin-bottom: 0.75rem; }
.cta p { color: var(--fg-muted); max-width: 30rem; margin-inline: auto; }
.cta .hero-actions { justify-content: center; margin-top: 1.75rem; }

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

.site-foot {
  border-top: 1px solid var(--border);
  padding: 2.5rem 0;
  font-size: 0.875rem;
  color: var(--fg-muted);
}

.site-foot-inner {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 2rem;
  align-items: baseline;
}

.site-foot a { color: var(--fg-muted); }
.site-foot p { margin: 0; }
.site-foot nav { display: flex; gap: 1.25rem; margin-left: auto; }

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

@media (max-width: 46rem) {
  body { font-size: 16px; }
  .wrap { padding: 0 1.125rem; }
  section { padding: 3.5rem 0; }
  .hero { padding: 4rem 0 3.5rem; }
  h1 { font-size: 2rem; }
  h2 { font-size: 1.5rem; }
  .lede { font-size: 1.0625rem; }

  .site-head-inner { flex-wrap: wrap; gap: 0 1rem; min-height: 0; padding: 0.875rem 0; }
  .brand { margin-right: auto; }
  .site-nav { order: 3; flex: 1 0 100%; padding-top: 0.75rem; gap: 1rem; }
  .site-foot nav { margin-left: 0; flex: 1 0 100%; }
}

@media (max-width: 26rem) {
  .hero-actions .btn { width: 100%; text-align: center; }
}