.mui-avatar {
  $diameter: 40px;
  @include circle($diameter);
  @include display-center();

  @extend %mui-font-style-headline;
  margin: 0;
  padding: 0;

  color: white;
  background-color: grey;

  * {
    @include display-center();
  }

  img {
    @include clip-circle($diameter);
    background-color: transparent;
  }
}