message: Avatar: new types; allowed children always; updated demo
diff: box-sizing: border-box;
  }
  + .Avatar__in {
  + position: relative;
  + color: var(--light-gray);
  + }
  +
  .Avatar__img {
  - border-radius: 50%;
  background-color: var(--placeholder-background);
  - color: var(--light-gray);
  border: none;
  display: block;
  max-width: 100%;
  + position: relative;
  + z-index: 1;
  }
  - div.Avatar__img {
  + .Avatar__children {
  + position: absolute;
  + left: 0;
  + top: 0;
  + z-index: 2;
  + width: 100%;
  + height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  