/**
 * Represents the UI layer for an Advantage high-impact format.
 * This class extends the HTMLElement class and provides methods for manipulating the UI content and styles.
 * @noInheritDoc
 */
export declare class AdvantageUILayer extends HTMLElement {
    #private;
    slotName: string;
    /**
     * Creates an instance of AdvantageUILayer.
     * Attaches a shadow root to the element and initializes the necessary elements.
     */
    constructor();
    /**
     * Changes the content of the UI layer.
     * @param content - The new content to be displayed. It can be either a string or an HTMLElement.
     */
    changeContent(content: string | HTMLElement): void;
    /**
     * Inserts CSS styles into the UI layer.
     * @param CSS - The CSS styles to be inserted.
     */
    insertCSS(CSS: string): void;
}