:root {
  color-scheme: light dark;
  --page: #f5f5f7;
  --surface: rgba(255, 255, 255, 0.76);
  --bar: rgba(245, 245, 247, 0.82);
  --ink: #1d1d1f;
  --muted: #6e6e73;
  --line: rgba(60, 60, 67, 0.18);
  --link: #0066cc;
  --accent: #007aff;
  --accent-soft: rgba(0, 122, 255, 0.08);
  --accent-line: rgba(0, 122, 255, 0.3);
  /* White text on this blue is 4.7:1, so the button label passes WCAG AA in both appearances. */
  --button: #0071e3;
  --radius: 22px;
  --measure: 760px;
}

* { box-sizing: border-box; }

html { scroll-padding-top: 76px; }

body {
  margin: 0;
  background: var(--page);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", sans-serif;
  font-size: 17px;
  line-height: 1.52;
  text-rendering: optimizeLegibility;
  -webkit-text-size-adjust: 100%;
}

a { color: var(--link); text-underline-offset: 0.16em; }

a:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 2px;
  border-radius: 4px;
}

.wrap,
main {
  width: min(100% - 40px, var(--measure));
  margin: 0 auto;
}

.skip-link {
  position: absolute;
  top: 8px;
  left: 8px;
  z-index: 10;
  padding: 8px 14px;
  border-radius: 999px;
  background: var(--ink);
  color: var(--page);
  font-weight: 600;
  text-decoration: none;
  transform: translateY(-160%);
}

.skip-link:focus { transform: none; }

/* Header and navigation */

.site-header {
  position: sticky;
  top: 0;
  z-index: 5;
  border-bottom: 1px solid var(--line);
  background: var(--bar);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  backdrop-filter: saturate(180%) blur(20px);
}

.site-header .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  min-height: 52px;
}

.brand {
  color: var(--ink);
  font-size: 19px;
  font-weight: 700;
  letter-spacing: -0.02em;
  text-decoration: none;
}

.site-nav {
  display: flex;
  gap: 4px;
}

.site-nav a {
  padding: 6px 12px;
  border-radius: 999px;
  color: var(--muted);
  font-size: 15px;
  font-weight: 500;
  text-decoration: none;
}

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

.site-nav a[aria-current="page"] {
  background: var(--accent-soft);
  color: var(--ink);
  font-weight: 600;
}

/* Page content */

main { padding: 64px 0 40px; }

.eyebrow {
  margin: 0 0 12px;
  color: var(--muted);
  font-size: 15px;
  font-weight: 600;
}

h1, h2 { letter-spacing: -0.025em; }

h1 {
  margin: 0;
  font-size: clamp(38px, 7vw, 56px);
  line-height: 1.04;
}

h2 {
  margin: 0 0 10px;
  font-size: 22px;
  line-height: 1.2;
}

.lede {
  max-width: 620px;
  margin: 22px 0 0;
  color: var(--muted);
  font-size: 20px;
}

.meta {
  margin: 20px 0 0;
  color: var(--muted);
  font-size: 15px;
}

.lede + .card,
.meta + .card { margin-top: 36px; }

.card {
  margin: 16px 0;
  padding: 26px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
}

.card > :first-child { margin-top: 0; }
.card > :last-child { margin-bottom: 0; }

p { margin: 0 0 14px; }
ul, ol { margin: 0 0 14px; padding-left: 22px; }
li + li { margin-top: 8px; }

.callout {
  border-color: var(--accent-line);
  background: var(--accent-soft);
}

.note {
  color: var(--muted);
  font-size: 15px;
}

.button {
  display: inline-block;
  padding: 11px 18px;
  border-radius: 999px;
  background: var(--button);
  color: white;
  font-weight: 600;
  text-decoration: none;
}

.button:hover { filter: brightness(1.06); }

/* Table of contents */

.toc h2 {
  color: var(--muted);
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0;
}

.toc ol {
  columns: 2 240px;
  column-gap: 32px;
  margin: 0;
  padding-left: 20px;
}

.toc li {
  margin: 0 0 6px;
  break-inside: avoid;
}

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

.toc a { text-decoration: none; }
.toc a:hover { text-decoration: underline; }

/* Contact details */

.details {
  margin: 4px 0 16px;
  border-top: 1px solid var(--line);
}

.details div {
  display: flex;
  flex-wrap: wrap;
  gap: 2px 16px;
  padding: 10px 0;
  border-bottom: 1px solid var(--line);
}

.details dt {
  flex: 0 0 110px;
  color: var(--muted);
}

.details dd {
  flex: 1 1 220px;
  margin: 0;
  font-weight: 500;
  overflow-wrap: anywhere;
}

/* Footer */

.site-footer {
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 14px;
}

.site-footer .wrap { padding: 28px 0 56px; }

.site-footer p { margin: 0 0 8px; }

.footer-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 20px;
  margin-bottom: 16px;
}

.footer-nav a {
  color: var(--ink);
  font-weight: 500;
  text-decoration: none;
}

.footer-nav a:hover { text-decoration: underline; }

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

@media (prefers-color-scheme: dark) {
  :root {
    --page: #000;
    --surface: rgba(44, 44, 46, 0.74);
    --bar: rgba(22, 22, 23, 0.8);
    --ink: #f5f5f7;
    --muted: #a1a1a6;
    --line: rgba(235, 235, 245, 0.18);
    --link: #2997ff;
    --accent: #0a84ff;
    --accent-soft: rgba(10, 132, 255, 0.16);
    --accent-line: rgba(10, 132, 255, 0.4);
  }
}

@media (max-width: 600px) {
  .wrap, main { width: min(100% - 32px, var(--measure)); }
  main { padding-top: 40px; }
  .card { padding: 21px; border-radius: 18px; }
  .brand { font-size: 17px; }
  .site-nav a { padding: 6px 10px; }
}

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

@media print {
  .site-header, .skip-link, .toc { display: none; }
  body { background: white; color: black; }
  .card { border-color: #ccc; background: none; box-shadow: none; }
}