How to change the color of the mat-label in a mat-form-field

Question

I need to change the color of my mat-label, but when I change by css using the "! Important", I lose the red color when my field is invalid.. how to change the color of my label without losing the red color when it is invalid?

      <mat-form-field floatLabel="always" appearance="none">
        <mat-label>Usuário</mat-label>
        <input autofocus matInput formControlName="j_username">
      </mat-form-field>