app-loading.css

#app-loading,
#app-loading:before,
#app-loading:after {
  border-radius: 50%;
  width: 2.5em;
  height: 2.5em;
  -webkit-animation-fill-mode: both;
  animation-fill-mode: both;
  -webkit-animation: loadingAnimation 1.8s infinite ease-in-out;
  animation: loadingAnimation 1.8s infinite ease-in-out;
}

#app-loading {
  color: #409eff;
  font-size: 10px;
  margin: 80px auto;
  position: relative;
  text-indent: -9999em;
  -webkit-transform: translateZ(0);
  -ms-transform: translateZ(0);
  transform: translateZ(0);
  -webkit-animation-delay: -0.16s;
  animation-delay: -0.16s;
  top: 0;
  transform: translate(-50%, 0);
}

#app-loading:before,
#app-loading:after {
  content: "";
  position: absolute;
  top: 0;
}

#app-loading:before {
  left: -3.5em;
  -webkit-animation-delay: -0.32s;
  animation-delay: -0.32s;
}

#app-loading:after {
  left: 3.5em;
}

@-webkit-keyframes loadingAnimation {
  0%,
  80%,
  100% {
    box-shadow: 0 2.5em 0 -1.3em;
  }
  40% {
    box-shadow: 0 2.5em 0 0;
  }
}

@keyframes loadingAnimation {
  0%,
  80%,
  100% {
    box-shadow: 0 2.5em 0 -1.3em;
  }
  40% {
    box-shadow: 0 2.5em 0 0;
  }
}