* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  overflow: hidden;
}
section {
  height: 100vh;
  overflow: hidden;
  background: #000;
}
section span {
  position: absolute;
  background: #fff;
  pointer-events: none;
  border-radius: 50%;
  background-size: cover;
}
.fadeout {
  animation-name: fadeout;
  animation-duration: 1.5s;
  animation-fill-mode: forwards;
}
@keyframes fadeout {
  0% {
    opacity: 1;
  }
  100% {
    opacity: 0;
  }
}