SOURCE

<div class="sk-chasing-dots">
  <div class="sk-child sk-dot1"></div>
  <div class="sk-child sk-dot2"></div>
</div>

body {
  background-color: #1abc9c;
}

.sk-chasing-dots {
  margin: 40px auto;
  width: 40px;
  height: 40px;
  position: relative;
  text-align: center;
  -webkit-animation: sk-chasingDotsRotate 2s infinite linear;
  animation: sk-chasingDotsRotate 2s infinite linear;
}

.sk-chasing-dots .sk-child {
  width: 60%;
  height: 60%;
  display: inline-block;
  position: absolute;
  top: 0;
  background-color: #FFF;
  border-radius: 100%;
  -webkit-animation: sk-chasingDotsBounce 2s infinite ease-in-out;
  animation: sk-chasingDotsBounce 2s infinite ease-in-out;
}

.sk-chasing-dots .sk-dot2 {
  top: auto;
  bottom: 0;
  -webkit-animation-delay: -1s;
  animation-delay: -1s;
}

@-webkit-keyframes sk-chasingDotsRotate {
  100% {
    -webkit-transform: rotate(360deg);
    transform: rotate(360deg);
  }
}

@keyframes sk-chasingDotsRotate {
  100% {
    -webkit-transform: rotate(360deg);
    transform: rotate(360deg);
  }
}

@-webkit-keyframes sk-chasingDotsBounce {
  0%,
  100% {
    -webkit-transform: scale(0);
    transform: scale(0);
  }
  50% {
    -webkit-transform: scale(1);
    transform: scale(1);
  }
}

@keyframes sk-chasingDotsBounce {
  0%,
  100% {
    -webkit-transform: scale(0);
    transform: scale(0);
  }
  50% {
    -webkit-transform: scale(1);
    transform: scale(1);
  }
}