.dot-loader {
  width: 60px;
  aspect-ratio: 2;
  --_g: no-repeat radial-gradient(circle closest-side, #000 90%, #0000);
  background:
    var(--_g) 0% 50%,
    var(--_g) 50% 50%,
    var(--_g) 100% 50%;
  background-size: calc(100%/3) 50%;
  animation: d3 1s infinite linear;
}

@keyframes d3 {
  20% {
    background-position: 0% 0%, 50% 50%, 100% 50%
  }

  40% {
    background-position: 0% 100%, 50% 0%, 100% 50%
  }

  60% {
    background-position: 0% 50%, 50% 100%, 100% 0%
  }

  80% {
    background-position: 0% 50%, 50% 50%, 100% 100%
  }
}