<div class="bar wave"></div>
<div class="bar wave"></div>
<div class="bar wave"></div>
<div class="bar wave"></div>
<div class="bar wave"></div>

html,body {
  display: flex;
  justify-content: center;
  align-items: center;
  
  width: 100%;
  height: 100%;
  background-color: #eaeaea;
}

.bar {
  width: 20px;
  height: 100px;
  margin: 0 2px;
}

@keyframes wave {
  0%, 50%, 100% { 
    background-color: orange; 
    transform: scale(1);
  }
  25% {
    background-color: yellow;
    transform: scale(1, 2);
  }
  75% {
    background-color: red;
    transform: scale(1, 0.5);
  }
}

.wave {
  animation-name: wave;
  animation-duration: 2s;
  animation-iteration-count: infinite;
}