:root{--bg:#ffffff;--fg:#111}:root[data-theme=dark]{--bg:#0e0e0e;--fg:#f0f0f0}body{background:var(--bg);color:var(--fg);font-family:ui-sans-serif,system-ui,-apple-system,Segoe UI,Roboto}input,button,textarea{padding:8px}nav a{color:inherit;text-decoration:none;margin-right:8px}