metamask-extension/ui/app/components/ui/pulse-loader/index.scss

.pulse-loader {
  display: flex;

  &__loading-dot-one,
  &__loading-dot-two,
  &__loading-dot-three {
    background: $Blue-500;
    width: 9px;
    height: 9px;
    margin-right: 2px;
    border-radius: 100%;
    animation-fill-mode: both;
  }

  &__loading-dot-one {
    -webkit-animation: loading-dot 0.75s 0.12s infinite cubic-bezier(0.2, 0.68, 0.18, 1.08);
    animation: loading-dot 0.75s 0.12s infinite cubic-bezier(0.2, 0.68, 0.18, 1.08);
  }

  &__loading-dot-two {
    -webkit-animation: loading-dot 0.75s 0.24s infinite cubic-bezier(0.2, 0.68, 0.18, 1.08);
    animation: loading-dot 0.75s 0.24s infinite cubic-bezier(0.2, 0.68, 0.18, 1.08);
  }

  &__loading-dot-three {
    -webkit-animation: loading-dot 0.75s 0.36s infinite cubic-bezier(0.2, 0.68, 0.18, 1.08);
    animation: loading-dot 0.75s 0.36s infinite cubic-bezier(0.2, 0.68, 0.18, 1.08);
  }

  @-webkit-keyframes loading-dot {
    0% {
      transform: scale(1);
      opacity: 1;
    }

    45% {
      transform: scale(0.7);
      opacity: 0.7;
    }

    80% {
      transform: scale(1);
      opacity: 1;
    }
  }

  @keyframes loading-dot {
    0% {
      transform: scale(1);
      opacity: 1;
    }

    45% {
      transform: scale(0.7);
      opacity: 0.7;
    }

    80% {
      transform: scale(1);
      opacity: 1;
    }
  }
}