<div class="zippy zippy-{{type}}" [ngClass]="{'zippy-empty': empty}">
  <div class="zippy-title" (click)="toggle()">
    <span class="zippy-indicator">{{ visible ? '&#9662;' : '&#9656;' }}</span>
    {{title}}
  </div>
  <div class="zippy-content" [ngClass]="{'zippy-hidden': !visible}">
    <ng-content></ng-content>
  </div>
</div>