export declare function pxToRem(num?: number | string | null): string | undefined;
export declare function isCalcSize(num: string): RegExpMatchArray | null;
export declare function isPercentSize(num: string): boolean;
export declare function toPx(num?: number | string | null, getRelationSize?: (unit: 'vh' | 'vw' | '%' | 'em') => number | undefined): number | undefined;