:root{--bg:#ffffff;--fg:#1a1a1a;--muted:#666666;--accent:#2196f3}@media (prefers-color-scheme:dark){:root{--bg:#121212;--fg:#f0f0f0;--muted:#a0a0a0;--accent:#64b5f6}}*{box-sizing:border-box}body{margin:0;min-height:100dvh;display:grid;place-items:center;padding:16px;background:var(--bg);color:var(--fg);font-family:system-ui,-apple-system,sans-serif;text-align:center}main{max-width:420px}h1{font-size:2rem;margin:0 0 8px}p{color:var(--muted);line-height:1.5}button{margin-top:16px;padding:12px 24px;border:0;border-radius:999px;background:var(--accent);color:#ffffff;font-size:1rem;cursor:pointer}button:disabled{opacity:.6;cursor:default}button+button{margin-left:8px}