/**
 * Finds the nearest CSS RGB colour in a palette to a given CSS RGB colour.
 *
 * @param {string} colour - The CSS RGB colour to find the nearest match for. Alpha channel is ignored.
 * @param {string[]} palette - An array of CSS RGB colours to search for the nearest match.
 * @returns {string} The CSS RGB colour in the palette that is closest to the given colour.
 * If the palette has fewer than 2 colours, or if it is undefined or null, the original colour is returned.
 * The CSS RGB colour string is in the format `rgb(R G B)`.
 */
export declare function findNearestCSSRGBColour(colour: string, palette: string[]): string;