.app{max-width:640px;margin:4rem auto;padding:0 1.5rem;text-align:center;font-family:system-ui,-apple-system,sans-serif}.app button{padding:.6rem 1.2rem;font-size:1rem;border-radius:8px;border:1px solid #ccc;cursor:pointer}:root{color-scheme:light dark}body{margin:0;background:#fafafa;color:#222}@media (prefers-color-scheme: dark){body{background:#111;color:#eee}}