:root {
  --bg: #f7f9fc; --fg: #16202c; --muted: #55657a; --accent: #2f5d8a; --card: #ffffff;
  color-scheme: light dark;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #0f1620; --fg: #e6edf5; --muted: #9fb0c3; --accent: #8fb8e4; --card: #182230; }
}
* { box-sizing: border-box; }
body {
  margin: 0; background: var(--bg); color: var(--fg);
  font: 16px/1.6 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}
main { max-width: 720px; margin: 0 auto; padding: 48px 16px; }
h1 { font-size: 2rem; margin: 0 0 8px; letter-spacing: -0.02em; }
h2 { font-size: 1.2rem; margin-top: 32px; }
p, li { color: var(--muted); }
a { color: var(--accent); }
.card { background: var(--card); border-radius: 18px; padding: 24px; margin: 24px 0; }
.code { font-size: 2.4rem; font-weight: 800; letter-spacing: 0.3em; color: var(--fg); }
.btn {
  display: inline-block; background: var(--accent); color: var(--bg); text-decoration: none;
  padding: 12px 20px; border-radius: 12px; font-weight: 600; margin: 4px 8px 4px 0;
}
.logo {
  width: 64px; height: 64px; border-radius: 18px; background: var(--accent);
  display: grid; place-items: center; font-size: 34px; margin-bottom: 16px;
}
footer { margin-top: 48px; font-size: 0.9rem; color: var(--muted); }