we_bstly-web/src/app/app.component.ts

import { Component } from '@angular/core';

import { I18nService } from './services/i18n.service';
import { DateAdapter } from '@angular/material/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html'
})

export class AppComponent {

  constructor(
    private i18n: I18nService,
    private _adapter: DateAdapter<any>) {
  }

  ngOnInit() {
    this._adapter.setLocale(this.i18n.getLocale());
    if (localStorage.getItem("bstly.darkTheme") == "true") {
      window.document.body.classList.add("dark-theme");
    }
  }

}