import { ContentObserver } from '@angular/cdk/observers'; import { Theme } from '../theme'; import { ThemeRegistryService } from './theme-registry.service'; import * as i0 from "@angular/core"; /** * A service that manages the activation and deactivation of themes. * * The service uses the `ContentObserver` service to observe changes in the `` element * and updates the {@link ThemeRegistryService internal theme registry} * when new `