SOURCE

<div id="app">
  <div class="loading">
    <div class="obj">
    </div>
    <div class="obj">
    </div>
    <div class="obj">
    </div>
    <div class="obj">
    </div>
    <div class="obj">
    </div>
    <div class="obj">
    </div>
    <div class="obj">
    </div>
    <div class="obj">
    </div>
  </div>
</div>

.loading {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  display: flex;
  align-items: center;
}

.obj {
  width: 7px;
  height: 150px;
  background: red;
  margin: 0 5px;
  border-radius: 5px;
  animation: load 0.8s infinite;
}

@keyframes load {
  0% {
    height: 3px;
  }
  100% {
    height: 150px;
  }
}