import { Ref } from 'vue';
export interface UseThemeReturn {
    isDark: Ref<boolean>;
    toggleTheme: () => void;
    setTheme: (theme: 'light' | 'dark') => void;
}
/** Reads and toggles the active theme (light/dark/system) with reactivity to OS preference changes. */
export declare function useTheme(): UseThemeReturn;