/**
 * If the display is monochrome (e.g. black&white), the value will be ≥0 and will mean the number of bits per pixel.
 * If the display is not monochrome, the returned value will be 0.
 * If the browser doesn't support this feature, the returned value will be undefined.
 *
 * @see https://developer.mozilla.org/en-US/docs/Web/CSS/@media/monochrome
 */
export default function getMonochromeDepth(): number | undefined;