:root{color-scheme:light dark}
*{box-sizing:border-box}
body{margin:0;min-height:100dvh;display:flex;align-items:center;justify-content:center;
  font:16px/1.5 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif;
  background:#fff;color:#111;text-align:center;padding:24px}
.c{width:100%;max-width:360px}
h1{font-size:22px;font-weight:600;margin:0 0 6px}
p{opacity:.65;margin:0 0 24px}
a.b{display:block;margin-top:12px;padding:15px 20px;border-radius:12px;background:#111;color:#fff;
  text-decoration:none;font-weight:600}
@media(prefers-color-scheme:dark){body{background:#0f1115;color:#e8eaed}a.b{background:#e8eaed;color:#111}}