:root {
  --bg: #ffffff;
  --surface: #f3f4f6;
  --text: #111827;
  --muted: #4b5563;
  --line: #e5e7eb;
  --accent: #374151;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #111827; --surface: #1f2937; --text: #f9fafb; --muted: #9ca3af; --line: #374151; --accent: #e5e7eb; }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.65 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}
header, main, footer { max-width: 760px; margin: 0 auto; padding: 0 20px; }
header { display: flex; align-items: center; gap: 12px; padding-top: 28px; padding-bottom: 8px; }
header img { width: 40px; height: 40px; border-radius: 10px; }
header a { color: var(--text); text-decoration: none; font-weight: 700; letter-spacing: 1.5px; font-size: 20px; }
nav { margin-left: auto; display: flex; gap: 18px; font-size: 15px; }
nav a { color: var(--muted); font-weight: 500; letter-spacing: 0; font-size: 15px; }
h1 { font-size: 30px; line-height: 1.25; margin: 28px 0 6px; }
h2 { font-size: 20px; margin: 32px 0 6px; }
p, li { color: var(--text); }
.muted { color: var(--muted); }
.card { background: var(--surface); border-radius: 18px; padding: 20px 22px; margin: 18px 0; }
a { color: var(--accent); }
hr { border: 0; border-top: 1px solid var(--line); margin: 40px 0; }
footer { color: var(--muted); font-size: 14px; padding-top: 24px; padding-bottom: 40px; }