.stars,
.stars2,
.stars3 {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  width: 100%;
  height: 100%;
  display: block;
  z-index: -3;
}

.stars {
  animation: animStar 91s linear infinite;
}

.stars2 {
  animation: animStar 156s linear infinite;
}

.stars3 {
  animation: animStar 221s linear infinite;
}

.star {
  position: absolute;
  border-radius: 50%;
}

@keyframes animStar {
  from {
    transform: translateY(0px);
  }
  to {
    transform: translateY(-2000px);
  }
}