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import { useEffect, useState } from "react"; /** * Returns `true` when the user's system prefers a dark color scheme. * Reactive: updates when the media query changes. */export function useIsDark(): boolean {  const [dark, setDark] = useState<boolean>(() => {    if (typeof window === "undefined") return false;    return window.matchMedia("(prefers-color-scheme: dark)").matches;  });   useEffect(() => {    if (typeof window === "undefined") return;    const mql = window.matchMedia("(prefers-color-scheme: dark)");    const handler = (event: MediaQueryListEvent) => setDark(event.matches);    mql.addEventListener("change", handler);    return () => mql.removeEventListener("change", handler);  }, []);   return dark;}