[data-slot="avatar"]:not(.is-assistant [data-slot="avatar"]) {
  isolation: isolate;
}

[data-slot="avatar"]:not(.is-assistant [data-slot="avatar"])::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 1;
  border-radius: inherit;
  background: #fff url("/custom-user-avatar/user-avatar-v1.png") center / contain no-repeat;
  pointer-events: none;
}