Show prettier empty mempool blocks.

frontend/src/app/components/mempool-blocks/mempool-blocks.component.html

@@ -27,7 +27,6 @@
         <span class="animated-border"></span>
       </div>
     </ng-template>
-    <div *ngIf="mempoolBlocks?.length === 0" class="bitcoin-block mempool-block empty-block">Mempool is empty</div>
   </div>
   <div *ngIf="arrowVisible" id="arrow-up" [ngStyle]="{'right': rightPosition + 75 + 'px', transition: transition }"></div>
 </div>