message: Corrected tooltip position in score-board
diff: <mat-header-cell *matHeaderCellDef> Status </mat-header-cell>
  <mat-cell *matCellDef="let challenge">
  <button mat-button [style.backgroundColor]="challenge.solved ? 'green': 'red'">
  - <span [hidden]="challenge.solved" id="{{challenge.name}}.notSolved" class="not-solved" (click)="openHint(challenge)" [ngClass]="{ 'label-button': showChallengeHints && challenge.hintUrl }" matTooltip="{{ showChallengeHints ? challenge.hint : null }}">
  + <span [hidden]="challenge.solved" id="{{challenge.name}}.notSolved" class="not-solved" (click)="openHint(challenge)" [ngClass]="{ 'label-button': showChallengeHints && challenge.hintUrl }" matTooltip="{{ showChallengeHints ? challenge.hint : null }}" matTooltipPosition="above">
  <i class="fas fa-book" aria-hidden="true" [hidden]="!showChallengeHints || !(challenge.hint || challenge.hintUrl)"></i>
  <span>Unsolved</span>
  </span>
  - <span [hidden]="!challenge.solved" id="{{challenge.name}}.solved" class="solved" (click)="repeatNotification(challenge)" [ngClass]="{ 'label-button': allowRepeatNotifications }" matTooltip="{{ allowRepeatNotifications ? ('NOTIFICATION_RESEND_INSTRUCTIONS') : null }}">
  + <span [hidden]="!challenge.solved" id="{{challenge.name}}.solved" class="solved" (click)="repeatNotification(challenge)" [ngClass]="{ 'label-button': allowRepeatNotifications }" matTooltip="{{ allowRepeatNotifications ? ('NOTIFICATION_RESEND_INSTRUCTIONS') : null }}" matTooltipPosition="above">
  <i class="far fa-flag" aria-hidden="true" [hidden]="!allowRepeatNotifications"></i>
  <span>Solved</span>
  </span>
  