.spinner {
  --size: 30px;
  --color: white;
  width: 100px;
  height: 100px;
  position: relative;
}

.spinner::after,.spinner::before {
  box-sizing: border-box;
  position: absolute;
  content: "";
  width: var(--size);
  height: var(--size);
  top: 50%;
  animation: up 2.4s cubic-bezier(0, 0, 0.24, 1.21) infinite;
  left: 50%;
  background: var(--color);
  box-shadow: 0 0 calc(var(--size) / 3) rgba(0, 0, 0, 0.25);
}

.spinner::after {
  background: var(--color);
  top: calc(50% - var(--size));
  left: calc(50% - var(--size));
  animation: down 2.4s cubic-bezier(0, 0, 0.24, 1.21) infinite;
}

@keyframes down {
  0%, 100% {
    transform: none;
  }

  25% {
    transform: translateX(100%);
  }

  50% {
    transform: translateX(100%) translateY(100%);
  }

  75% {
    transform: translateY(100%);
  }
}

@keyframes up {
  0%, 100% {
    transform: none;
  }

  25% {
    transform: translateX(-100%);
  }

  50% {
    transform: translateX(-100%) translateY(-100%);
  }

  75% {
    transform: translateY(-100%);
  }
}