articles.component.html

<div [class]="getClass()">
  <article *ngIf="articles$ | async as articles">
    <div *ngFor="let article of articles">
      <app-article-component
        [article]="article"
      ></app-article-component>
      <hr *ngIf="article !== articles[articles.length - 1]">
    </div>
  </article>
</div>