<div class="md-form">
    <input mdbActive type="text" formControlName="name" id="name" class="form-control">
    <label for="name">Clan name</label>
    <small *ngIf="clanForm.get('name').invalid && clanForm.get('name').touched" class="text-danger">Clan name should be given</small>
  </div>

input.ng-invalid.ng-touched {
  border-bottom-color: #ff0000;
  border-bottom: 1px solid #ff0000;
}