.gallery{
  position:relative;  
  width:300px;
  height:200px;
  transform-style:preserve-3d;
  animation:rotate 35s linear infinite;
}

@keyframes rotate{
  from{
    transform:perspective(1200px) rotateY(0deg);
  }
  
  to{
    transform:perspective(1200px) rotateY(360deg);
  }
}

.gallery span{
  position:absolute;
  width:100%;
  height:100%;
  transform-origin:center;
  transform-style:preserve-3d;
  transform:rotateY(calc(var(--i) * 45deg)) translateZ(380px);
}

.gallery span img{
  position:absolute;
  width:100%;
  height:100%;
  object-fit:cover;
}