<template>
  <div class="bars">
    <div class="bar" v-for="item in 10" :key="item"/>
  </div>
</template>

<style scoped>
  /* loading.css */
.bars {
  height: 30px;
  left: 50%;
  margin: -30px 0 0 -20px;
  position: absolute;
  top: 60%;
  width: 40px;
}
.bar {
 background: #e04960;
  bottom: 1px;
  height: 3px;
  position: absolute;
  width: 3px;      
  animation: sound 0ms -800ms linear infinite alternate;
}
@keyframes sound {
  0% {
     opacity: .35;
      height: 3px; 
  }
  100% {
      opacity: 1;       
      height: 28px;        
  }
}
.bar:nth-child(1)  { left: 1px; animation-duration: 474ms; }
.bar:nth-child(2)  { left: 5px; animation-duration: 433ms; }
.bar:nth-child(3)  { left: 9px; animation-duration: 407ms; }
.bar:nth-child(4)  { left: 13px; animation-duration: 458ms; }
.bar:nth-child(5)  { left: 17px; animation-duration: 400ms; }
.bar:nth-child(6)  { left: 21px; animation-duration: 427ms; }
.bar:nth-child(7)  { left: 25px; animation-duration: 441ms; }
.bar:nth-child(8)  { left: 29px; animation-duration: 419ms; }
.bar:nth-child(9)  { left: 33px; animation-duration: 487ms; }
.bar:nth-child(10) { left: 37px; animation-duration: 442ms; }
</style>