/**
 * @class FontSizeChanger
 * @description A component to change the base font size of the host page.
 * For this to not affect the widget, the widget's internal components must
 * use px or em units for sizing, not rem.
 */
export declare class FontSizeChanger extends HTMLElement {
    private shadow;
    private currentModeIndex;
    private toneCard;
    private toneCardContent;
    constructor();
    connectedCallback(): void;
    disconnectedCallback(): void;
    private attachListeners;
    private removeListeners;
    private handleClick;
    /**
     * Applies the font scaling to the host page only. It does not
     * attempt to insulate the widget itself.
     */
    private applyMode;
    private loadState;
    private saveState;
    private handleReset;
    private updateUI;
    private render;
}