/**
 * Base dialog component that extends HTMLElement
 * Provides common dialog functionality with header, close button, and content area
 *
 * Usage:
 * ```typescript
 * const dialog = document.createElement('dialog-component');
 * dialog.setAttribute('header', 'Dialog Title');
 * dialog.innerHTML = '<p>Your content goes here</p>';
 * dialog.showModal(); // Don't append to body, just call showModal()
 * ```
 *
 * Features:
 * - Header with customizable text
 * - Close button
 * - Click outside to close
 * - ESC key to close
 * - Automatic cleanup on close
 *
 * Important: Only one instance of this component should be added to the DOM at any time.
 * Multiple instances may cause conflicts with event listeners and cleanup behavior.
 */
export declare class DialogComponent extends HTMLElement {
    private dialog;
    private backdrop;
    private _escHandler;
    private _focusTrapHandler;
    private _previouslyFocused;
    constructor();
    /**
     * Observed attributes for the component
     */
    static get observedAttributes(): string[];
    /**
     * Inject dialog styles into document head
     * Prevents duplicate injection by checking for existing styles
     */
    private injectStyles;
    /**
     * Render the dialog
     */
    private render;
    /**
     * Setup event listeners for closing the dialog
     */
    private setupEventListeners;
    /**
     * Show the dialog (alias for showModal)
     */
    show(): void;
    /**
     * Show the dialog as modal
     */
    showModal(): void;
    /**
     * Close the dialog
     */
    close(): void;
    /**
     * Cleanup when dialog is closed
     */
    private cleanup;
    /**
     * Called when component is removed from DOM
     */
    disconnectedCallback(): void;
    /**
     * Called when observed attributes change
     */
    attributeChangedCallback(name: string, _oldValue: string, newValue: string): void;
}