:root{font-family:ui-sans-serif,system-ui,-apple-system,Segoe UI,Roboto,Ubuntu,Cantarell,Noto Sans,Arial,sans-serif;color:#0f172a;background:#f8fafc}*{box-sizing:border-box}body{margin:0}.app-shell{max-width:960px;margin:0 auto;padding:48px 24px}