body {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}
.loader {
  display: flex;
}

.bar {
  width: 6px;
  height: 20px;
  margin: 0 4px;
  background-color: #000;
  border-radius: 4px;
  animation: loader 1s ease-in-out infinite;
}
.bar:nth-child(1) {
  animation-delay: 0s;
}

.bar:nth-child(2) {
  animation-delay: 0.1s;
}

.bar:nth-child(3) {
  animation-delay: 0.2s;
}

.bar:nth-child(4) {
  animation-delay: 0.3s;
}

.bar:nth-child(5) {
  animation-delay: 0.4s;
}
@keyframes loader {
  0% {
    transform: scale(1);
  }
  20% {
    transform: scale(1, 2);
  }
  40% {
    transform: scale(1);
  }
}