.item1, .item2, .item3 {
  position: absolute;
  background-color: transparent;
  left: calc(50% - (var(--size) / 2));
  top: calc(50% - (var(--size) / 2));
  height: var(--size);
  width: var(--size);
  border-radius: 50%;
}

.loader .item1 {
  --size: 90px;
  animation: size1_1 2.5s infinite alternate;
  z-index: 1;
}

.loader .item2 {
  --size: 60px;
  animation: size1_2 2.5s infinite alternate;
  z-index: 2;
}

.loader .item3 {
  --size: 30px;
  animation: size1_3 2.5s infinite alternate;
  z-index: 3;
}

@keyframes size1_1 {
  0%,
  10% {
    transform: scale(0);
  }

  100% {
    transform: scale(1);
    box-shadow: 8px 8px 14px #c5c5c5, -8px -8px 14px #ffffff;
  }
}

@keyframes size1_2 {
  0%,
  40% {
    transform: scale(0);
  }

  100% {
    transform: scale(1);
    box-shadow: 8px 8px 14px #c5c5c5, -8px -8px 14px #ffffff;
  }
}

@keyframes size1_3 {
  0%,
  70% {
    transform: scale(0);
  }

  100% {
    transform: scale(1);
    box-shadow: 8px 8px 14px #c5c5c5, -8px -8px 14px #ffffff;
  }
}