.spin-on-scroll {
  width: 600px;   /* increase this number */
  display: block;
  margin: 300px auto;
  transform-origin: center;
}


.spin-slow {
  animation: spin 30s linear infinite;
  top:50%;
  left:50%;
  translate: 2px 4px;

}

@keyframes spin {
  from {
    transform: rotate(0deg);
  }
  to {
    transform: rotate(360deg);
  }
}