import React from 'react';const MOBILE_BREAKPOINT = 768;export function useIsMobile() {  const [isMobile, setIsMobile] = React.useState<boolean | undefined>(undefined);  React.useEffect(() => {    const mql = window.matchMedia(`(max-width: ${MOBILE_BREAKPOINT - 1}px)`);    const onChange = () => {      setIsMobile(window.innerWidth < MOBILE_BREAKPOINT);    };    mql.addEventListener('change', onChange);    setIsMobile(window.innerWidth < MOBILE_BREAKPOINT);    return () => mql.removeEventListener('change', onChange);  }, []);  return !!isMobile;}