blockscout/apps/block_scout_web/assets/css/components/_loading-spinner.scss

// ATTRIBUTION
//
// Author: Tobias Ahlin (tobiasahlin)
//
// SpinKit - Simple loading spinners animated with CSS.
// https://github.com/tobiasahlin/SpinKit

.loading-spinner {
  margin: auto 1rem;
  width: 40px;
  height: 40px;
  position: relative;
}

.loading-spinner-block-1,
.loading-spinner-block-2 {
  background-color: currentColor;
  width: 12px;
  height: 12px;
  position: absolute;
  top: 0;
  left: 0;
  border-radius: $border-radius;

  animation: loading-spinner 1.8s infinite ease-in-out;
}

.loading-spinner-block-2 {
  animation-delay: -0.9s;
}

@keyframes loading-spinner {
  25% {
    transform: translateX(22px) rotate(-90deg) scale(0.5);
  }
  50% {
    transform: translateX(22px) translateY(22px) rotate(-179deg);
  }
  50.1% {
    transform: translateX(22px) translateY(22px) rotate(-180deg);
  }
  75% {
    transform: translateX(0px) translateY(22px) rotate(-270deg) scale(0.5);
  }
  100% {
    transform: rotate(-360deg);
  }
}

.loading-spinner-small {
  display: inline-block;
  position: relative;
  top: -0.125em;
  margin: auto 0.5em auto 0;
  width: 1em;
  height: 1em;

  .loading-spinner-block-1,
  .loading-spinner-block-2 {
    width: 0.5em;
    height: 0.5em;

    animation: loading-spinner-small 1.8s infinite ease-in-out;
  }

  .loading-spinner-block-2 {
    animation-delay: -0.9s;
  }
}

@keyframes loading-spinner-small {
  25% {
    transform: translateX(10px) rotate(-90deg) scale(0.5);
  }
  50% {
    transform: translateX(10px) translateY(10px) rotate(-179deg);
  }
  50.1% {
    transform: translateX(10px) translateY(10px) rotate(-180deg);
  }
  75% {
    transform: translateX(0px) translateY(10px) rotate(-270deg) scale(0.5);
  }
  100% {
    transform: rotate(-360deg);
  }
}