export declare function getContrastColor({ backgroundColor, lightColor, darkColor, threshold, }: {
    backgroundColor: string;
    lightColor: string;
    darkColor: string;
    threshold?: number;
}): string;
export declare const injectStyle: (id: string, style: string) => void;
export declare function generateSecureString(length: number): string;
export declare function isObject(item: any): item is object;
export declare function deepMerge<T extends object, T2 extends object>(target: T, ...sources: T2[]): T;