import { TemplateResult } from '../../../../../lit-html/lit-html.js';
/**
 * Little CSS management helper dynamically adds
 * given render blocks (intended to be <style> blocks
 * form client components and applications) to the
 * head of a document.
 * Ex:
 *    ```
 * helper.componentCss.push( html`<style>...</style>` ); helper.render();
 *    ```
 * The helper renders the baseCss template results, then the componentCss,
 * and finally the appCss; so the idea is that:
 * - baseCss defines the base rules from the style guide
 * - componentCss defines extensions for styling each component
 * - appCss cascades application specific overrides and layout rules
 *
 * Note: StyleGuide.css.js includes an optional block of `<meta>` tags
 * that may be added to `helper.baseCss` if the html shell does
 * not already define the viewport and content-type.
 */
export declare class StyleHelper {
    baseCss: TemplateResult[];
    componentCss: TemplateResult[];
    appCss: TemplateResult[];
    render(): void;
}
export declare const singleton: StyleHelper;
export default singleton;