/** Contrasting text color based on background luminance: #rgb, #rrggbb or rgb(r, g, b). */
export declare function contrastTextColor(background: string): string;
/**
 * Opaque blend of two colors: `amount` 0 keeps `color`, 1 yields `towards`.
 * Lets a series tint a fill without painting it semi-transparent. Returns
 * `color` untouched when either side is not parseable.
 */
export declare function mixColors(color: string, towards: string, amount: number): string;