:root {
  --bg: #ffffff;
  --surface: #f5f5f7;
  --ink: #1d1d1f;
  --muted: #86868b;
  --border: #d2d2d7;
  --accent: #0071e3;
  --accent-ink: #ffffff;
  --maxw: 720px;
  --radius: 14px;
  color-scheme: light;
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 17px/1.6 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
}

/* Skip link */
.skip-link {
  position: absolute;
  left: 50%;
  top: -64px;
  transform: translateX(-50%);
  z-index: 100;
  padding: 10px 18px;
  background: var(--accent);
  color: var(--accent-ink);
  border-radius: 0 0 var(--radius) var(--radius);
  text-decoration: none;
  transition: top .15s ease;
}
.skip-link:focus { top: 0; }

/* Header / nav */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.8);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--border);
}
.nav {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 12px 20px;
  display: flex;
  align-items: center;
  gap: 8px 22px;
  flex-wrap: wrap;
}
.nav__brand {
  font-weight: 600;
  letter-spacing: -0.01em;
  margin-right: auto;
  color: var(--ink);
  text-decoration: none;
}
.nav__link {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.95rem;
  padding: 6px 4px;
  border-radius: 6px;
}
.nav__link:hover { color: var(--ink); }
.nav__link[aria-current="page"] { color: var(--ink); font-weight: 600; }

/* Main content */
main {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 48px 20px 64px;
}

h1 {
  font-size: clamp(1.8rem, 5vw, 2.4rem);
  line-height: 1.15;
  letter-spacing: -0.02em;
  margin: 0 0 0.6rem;
}
h2 {
  font-size: 1.2rem;
  letter-spacing: -0.01em;
  margin: 2rem 0 0.5rem;
}
p { margin: 0 0 1rem; }
.lead { font-size: 1.15rem; color: var(--ink); }
.meta { color: var(--muted); font-size: 0.9rem; margin-bottom: 1.5rem; }

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

ul { padding-left: 1.3rem; }
li { margin: 0.3rem 0; }

hr {
  border: none;
  border-top: 1px solid var(--border);
  margin: 56px 0;
}

/* Landing cards */
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
  margin-top: 28px;
  padding: 0;
  list-style: none;
}
.card {
  display: block;
  padding: 24px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--ink);
  transition: transform .15s ease, box-shadow .15s ease;
}
.card:hover {
  text-decoration: none;
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.06);
}
.card h2 { margin: 0 0 0.35rem; font-size: 1.1rem; }
.card p { margin: 0; color: var(--muted); }
.card__arrow { color: var(--accent); font-weight: 600; }

/* Footer */
.site-footer {
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.85rem;
  text-align: center;
  padding: 28px 20px;
}

/* Focus visibility */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 4px;
}

/* Utilities */
.visually-hidden {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

@media (max-width: 600px) {
  main { padding: 32px 18px 48px; }
  hr { margin: 40px 0; }
}