// overwrite the checkbox background
::ng-deep .mat-checkbox-checked .mat-checkbox-background, 
.mat-checkbox-indeterminate .mat-checkbox-background {
  background-color: black !important;
}

// overwrite the ripple overlay on hover and click
::ng-deep .mat-checkbox:not(.mat-checkbox-disabled) .mat-checkbox-ripple .mat-ripple-element {
  background-color: black !important;
}