JSFiddle - React, Tailwind, and code Playground

HTML

<div></div>

CSS

@keyframes nuage {
    from {left: -200px;}
    to {left: 100%;}
}

html, body {overflow: hidden;margin: 0;background: #20262E;}

div {
  position: absolute;
  width: 200px;
  height: 60px;
  top: 50%;
  left: -200px;
  background: #fff;
  border-radius: 50px;
  animation: nuage 5s infinite linear;
}

div:before, div:after {
  content: "";
  position: absolute;
  background: #fff;
  border-radius: 100%;
}

div:before {
  width: 100px;
  height: 100px;
  top: -55px;
  right: 30px;
}

div:after {
  width: 70px;
  height: 70px;
  top: -30px;
  left: 30px;
}