* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  background: #363c3e;
}

.loader {
  position: relative;
  width: 300px;
  height: 300px;
  transform-style: preserve-3d;
  transform: perspective(500px) rotateX(60deg);
}

.loader div {
  position: absolute;
  display: block;
  border: 3px solid #0bcbed;
  border-radius: 50%;
  top: calc(var(--i) * 10px);
  left: calc(var(--i) * 10px);
  right: calc(var(--i) * 10px);
  bottom: calc(var(--i) * 10px);
  transform: translateZ(-100px);
  animation: waving 3s ease-in-out infinite;
  animation-delay: calc(1.5s - var(--i) * 0.1s);
  animation-fill-mode: forwards;
  opacity: 0;
}

@keyframes waving {
  0%,
  100% {
    transform: translateZ(-100px);
    opacity: 0;
  }

  50% {
    transform: translateZ(100px);
    opacity: 1;
  }
}