message: Add class to total layers number
  With that addition nothing changes, but gives the ability to also style the total layers number.
diff: <span class="layer-indication" *ngIf="layerProgress && !(layerProgress.current === 0 && layerProgress.total === 0)">
  - Layer <span class="layer-indication__current-layer">{{ layerProgress.current }}</span> of {{ layerProgress.total }}
  + Layer <span class="layer-indication__current-layer">{{ layerProgress.current }}</span> of <span class="layer-indication__total-layers">{{ layerProgress.total }}</span>
  </span>
  