.loading-mask {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  z-index: 9999;
  width: 100%;
  height: 100%;
  background-color: rgba(60, 60, 60, .5);
  user-select: none;
}

.loading {
  width: 80px;
  height: 40px;
  line-height: 100vh;
  margin: auto;
  text-align: center;
}

.loading span {
  display: inline-block;
  width: 8px;
  height: 100%;
  border-radius: 4px;
  background: lightgreen;
  animation: load 1s ease infinite;
}

@keyframes load {
  0%,
  100% {
    height: 40px;
    background: lightgreen;
  }

  50% {
    height: 70px;
    margin: -15px 0;
    background: lightblue;
  }
}

.loading span:nth-child(2) {
  animation-delay: .2s;
}

.loading span:nth-child(3) {
  animation-delay: .4s;
}

.loading span:nth-child(4) {
  animation-delay: .6s;
}

.loading span:nth-child(5) {
  animation-delay: .8s;
}