ng-custom-properties#layout-setup.ts

interface Theme {
  primary: string;
  accent: string;
}

@Component({
  selector: 'app-root',
  template: `<app-card></app-card>`,
})
export class AppComponent {
  readonly indigoPinkTheme: Theme = {
    primary: '#5c6bc0',
    accent: '#ec407a'
  };

  readonly pinkBlueGrayTheme: Theme = {
    primary: '#ec407a',
    accent: '#90a4ae'
  };

  readonly deepPurpleAmberTheme: Theme = {
    primary: '#7e57c2',
    accent: '#ffca28'
  };

  theme: Theme = this.indigoPinkTheme;
}