<div class="loading">
  <span></span>
  <span></span>
  <span></span>
</div>

body{
  height:100vh;
  display:grid;
  place-items:center;
}
.loading {
  margin: 1rem 2rem;
  display: flex;
  justify-content: center;
  gap: 10px;
}

span {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  animation-name: sliding;
  animation-duration: 1.5s;
  animation-timing-function: ease-in-out;
  animation-iteration-count: infinite;
}

span:nth-child(1) {
  background-color: violet;
  animation-delay: 0.3s;
}
span:nth-child(2) {
  background-color: rgb(235, 86, 235);
  animation-delay: 0.4s;
}
span:nth-child(3) {
  background-color: rgb(201, 32, 201);
  animation-delay: 0.5s;
}

@keyframes sliding {
  20% {
    opacity: 0;
    transform: translateX(-500px);
  }
  70% {
    opacity: 0;
    transform: translateX(500px);
  }
  100% {
    opacity: 1;
    transform: translateX(0);
  }
}