/**
 * Flattens the CSS variables object into a string of CSS variables.
 *
 * @param {object} cssVariables - The CSS variables object to flatten.
 * @param {string} [prefix='colors'] - The prefix to add to the CSS variables.
 * @param {string} [parentKey=''] - The parent key to add to the CSS variables.
 * @returns {string} - The flattened CSS variables.
 */
export declare function flattenCssVariables(cssVariables: Record<string, unknown>, prefix?: string, parentKey?: string): string;