:root {
  --bg: #ffffff;
  --text: #1d1d1f;
  --muted: #6e6e73;
  --accent: #0a6cff;
  --card: #f5f5f7;
  --rule: #d2d2d7;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #000000;
    --text: #f5f5f7;
    --muted: #a1a1a6;
    --accent: #3b91ff;
    --card: #1c1c1e;
    --rule: #3a3a3c;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 17px/1.55 -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", Arial, sans-serif;
  -webkit-text-size-adjust: 100%;
}

main, header, footer {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 20px;
}

header {
  display: flex;
  align-items: center;
  gap: 12px;
  padding-top: 28px;
  padding-bottom: 8px;
}

header a { color: inherit; text-decoration: none; display: flex; align-items: center; gap: 12px; }
header img { width: 44px; height: 44px; }
header strong { font-size: 20px; }

nav { margin-left: auto; display: flex; gap: 18px; font-size: 15px; }
nav a { color: var(--muted); text-decoration: none; }
nav a[aria-current="page"], nav a:hover { color: var(--text); }

h1 { font-size: 34px; line-height: 1.15; margin: 32px 0 8px; letter-spacing: -0.01em; }
h2 { font-size: 22px; margin: 36px 0 8px; }
h3 { font-size: 18px; margin: 24px 0 4px; }
p, li { color: var(--text); }
.lead { font-size: 20px; color: var(--muted); margin-top: 0; }
.muted { color: var(--muted); font-size: 15px; }
a { color: var(--accent); }

.card {
  background: var(--card);
  border-radius: 14px;
  padding: 18px 20px;
  margin: 20px 0;
}

ol, ul { padding-left: 22px; }
li { margin: 6px 0; }

footer {
  border-top: 1px solid var(--rule);
  margin-top: 56px;
  padding-top: 18px;
  padding-bottom: 40px;
  color: var(--muted);
  font-size: 14px;
}

@media (max-width: 480px) {
  h1 { font-size: 28px; }
  nav { gap: 12px; }
}