.wave {
  text-align: center;
  font-size: 10px;
}
.wave .rect {
  display: inline-block;
  animation: waveStretchDelay 1.2s infinite ease-in-out;
}
.wave .rect1 {
  animation-delay: -1.2s;
}
.wave .rect2 {
  animation-delay: -1.1s;
}
.wave .rect3 {
  animation-delay: -1s;
}
.wave .rect4 {
  animation-delay: -0.9s;
}
.wave .rect5 {
  animation-delay: -0.8s;
}
@keyframes waveStretchDelay {
  0%, 40%, 100% {
    transform: scaleY(0.4);
  }
  20% {
    transform: scaleY(1);
  }
}