export declare namespace CSSUtils {
    const CLASS_PREFIX = "ns-";
    const MODAL_ROOT_VIEW_CSS_CLASS = "ns-modal";
    const ROOT_VIEW_CSS_CLASS = "ns-root";
    const ORIENTATION_CSS_CLASSES: string[];
    const SYSTEM_APPEARANCE_CSS_CLASSES: string[];
    const LAYOUT_DIRECTION_CSS_CLASSES: string[];
    /**
     * Classes describing the state of a single window. Two windows can legitimately
     * disagree on all of them, so they live on each window's root view (and the modals
     * presented over it) rather than in the process-wide system class list.
     */
    const WINDOW_SCOPED_CSS_CLASSES: string[];
    function getSystemCssClasses(): string[];
    function pushToSystemCssClasses(value: string): number;
    function removeSystemCssClass(value: string): string;
    function getModalRootViewCssClass(): string;
    function getRootViewCssClasses(): string[];
    function pushToRootViewCssClasses(value: string): number;
    function removeFromRootViewCssClasses(value: string): string;
}