export declare function hasClassnames(el: HTMLElement, ...classNames: string[]): boolean;
export declare function addClassnames(el: HTMLElement, ...classNames: string[]): HTMLElement;
export declare function removeClassnames(el: HTMLElement, ...classNames: string[]): HTMLElement;
export declare function removeClassnamesUnless(el: HTMLElement, classnamesToRemove: string[], classnamesToKeep: string[]): HTMLElement;
export declare function updateElementStyles(el: HTMLElement, ...styleTuples: [string, string][]): HTMLElement;
export declare function unsetElementStyles(el: HTMLElement, ...styleProperties: string[]): HTMLElement;
export declare function pxToRem(pxValue: number): string;
export declare function getCssPropertyValue(propertyName: string, el?: Element, pseudoSelectorModifier?: string | null): string;
export declare function setCssPropertyValue(propertyName: string, value: string | null | false, el?: Element): void;
export declare function isCssPropertyName(str: any): boolean;
export declare function supportsAdoptingStyleSheets(): any;