<div class="preloader">
  <div class="preloader__content">
    <div class="preloader__stick"></div>
    <div class="preloader__stick"></div>
    <div class="preloader__stick"></div>
    <div class="preloader__stick"></div>
    <div class="preloader__stick"></div>
  </div>
</div>
body {
  margin: 0;
}
.preloader {
  --size: 200px;
  --color: #7057a0;
  width: 100vw;
  height: 100vh;
  position: fixed;
  background: #34314c;
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
}

.preloader__content {
  position: relative;
  height: var(--size);
  width: var(--size);
  display: flex;
  justify-content: center;
  align-items: center;
}

.preloader__stick {
  width: 5%;
  margin-right: 3%;
  height: 25%;
  background: var(--color);
  animation-duration: 1.5s;
  animation-iteration-count: infinite;
  animation-timing-function: linear;
  animation-name: stick;
}

.preloader__stick:nth-child(1) {
  animation-delay: -1.2s;
}
.preloader__stick:nth-child(2) {
  animation-delay: -0.9s;
}
.preloader__stick:nth-child(3) {
  animation-delay: -0.6s;
}
.preloader__stick:nth-child(4) {
  animation-delay: -0.3s;
}
.preloader__stick:nth-child(5) {
  animation-delay: -0.0s;
}

@keyframes stick {
  0% {
    height: 25%;
  }
  10% {
    height: 50%;
  }
  20% {
    height: 25%;
  }
}

.preloader__stick:last-child {
  margin: 0;
}

External CSS

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External JavaScript

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