/**
 * Calculate the percentage of the rail that has been scrolled.
 * If the left edge is at the total minus the viewport we are done scrolling.
 * @param viewport window width
 * @param total total width of the rail
 * @param left left edge of scroll
 */
export declare const percentage: ({ viewport, total, left, }: {
    viewport: number;
    total: number;
    left: number;
}) => number;