post.component.html

<li [ngClass]="{'list-group-item': true,
                'list-group-item-success': postloveIts === 1,
                'list-group-item-danger': postloveIts === 0}">
  <p>Mis à jour :  {{ lastUpdate | async | date: 'mediumTime' | uppercase }}</p>
  <h4 [ngStyle]="{color: getColor()}">Posts : {{ postTitle }} -- LoveIts : {{ getLoveIts() }}</h4>
  <p>Content : {{ postContent }}</p>
  <button class="btn btn-success"
          (click)="onLove()">Love it</button>
  <button class="btn btn-danger"
          (click)="onDontLove()">Don't love it</button>
</li>