body{
  margin: 0;
  padding: 0;
}

.circle{
  width: 10px;
  height: 10px;
  background: red;
  border-radius: 50%;
  position: fixed;
  transform: translate(-50%,-50%);
  opacity: 0;
  animation: aa 1s 1;
}
@keyframes aa {
  0%{
    opacity: 0;
  }
  50%{
    opacity: 1;
  }
  100%{
    opacity: 0;
  }
}