.whole-canvas-selector {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;

  &__button {
    position: absolute;
    width: 100px;
    left: 50%;
    margin-left: -50px;
    top: 50%;
    z-index: 10;
  }
}