.background-img {
width: 10px;
height: 10px;
margin: 0 auto;
animation-name:img-ani;
animation-duration: 2s;
animation-timing-function: ease-in;
}
@keyframes img-ani {
from{opacity:0;}
to{opacity: 1;}
}
CSS
Image appear slowly css – Slow animation of image in css Code Example