import React from 'react';
export type OverlayPosition = 'top' | 'bottom';
export type OverlayStyle = {
    top?: number;
    bottom?: number;
    left: number;
    maxWidth: number;
    maxHeight: number;
} & React.CSSProperties;
export declare function useOverlay(anchorRef: React.RefObject<HTMLElement | null>, open: boolean, gap?: number, extraStyle?: React.CSSProperties): {
    position: OverlayPosition;
    style: OverlayStyle | null;
};
export declare function BitPortal({ children }: {
    children: React.ReactNode;
}): React.ReactPortal;