// Shared utilities: responsive hook + mobile-aware helpers
function useWindowWidth() {
  const [w, setW] = React.useState(window.innerWidth);
  React.useEffect(() => {
    const fn = () => setW(window.innerWidth);
    window.addEventListener('resize', fn, { passive: true });
    return () => window.removeEventListener('resize', fn);
  }, []);
  return w;
}
window.useWindowWidth = useWindowWidth;