message: Use ng-container to wrap z-w-s and button
  Zero-width-space must be wrapped together with button or else, when the button is not shown, there will be an extra zero-width-space which will throw the remaining elements out of alignment.
diff: @@ -23,15 +23,16 @@ import {
  <span>&lsaquo;</span>
  </button>
  + <ng-container *ngIf="calendar.monthTitle">
  &#8203; <!-- zero-width space needed for correct alignement
  with preserveWhitespaces: false in Angular -->
  <button class="current"
  - *ngIf="calendar.monthTitle"
  type="button"
  - (click)="view('month')">
  - <span>{{ calendar.monthTitle }}</span>
  + (click)="view('month')"
  + ><span>{{ calendar.monthTitle }}</span>
  </button>
  + </ng-container>
  &#8203; <!-- zero-width space needed for correct alignement
  with preserveWhitespaces: false in Angular -->
  