Function handler

ui/src/App.tsx:28–28

()

  useEffect(() => {
    const mq = window.matchMedia(query)
    const handler = () => setMatches(mq.matches)
    setMatches(mq.matches) // re-sync in case the query changed between renders
    mq.addEventListener('change', handler)
    return () => mq.removeEventListener('change', handler)