ion-avatar,
ion-thumbnail {
  width: 48px !important;
  height: 48px !important;
  padding: 0 !important;
  margin: 0 !important;
  font-size: 24px;
  line-height: 56px;
  vertical-align: middle;
  text-align: center;
}

ion-avatar {
  border-radius: 50%;
}