/**
 * @class ToneCardContent
 * @extends HTMLElement
 * @description Stateless content component that presents icon and label.
 * Relies on parent ToneCard for theming context via CSS custom properties.
 *
 * Architecture:
 * - No internal state management (stateless)
 * - Uses inherited CSS custom properties for theming
 * - Single responsibility: content presentation
 */
export declare class ToneCardContent extends HTMLElement {
    private shadow;
    private labelElement;
    static get observedAttributes(): string[];
    constructor();
    connectedCallback(): void;
    attributeChangedCallback(name: string, oldValue: string | null, newValue: string | null): void;
    private updateLabel;
    private render;
}