CODE EXAMPLE FOR CSS

moving cloud by css

#sky {
	overflow: hidden;
}
#clouds {
	width: 200%;
	height: 400px;
	background-image: url('pic.jpg');
	background-size: cover;
	-webkit-animation: movingclouds 25s linear infinite;
	-moz-animation: movingclouds 25s linear infinite;
	-o-animation: movingclouds 25s linear infinite;
}
@keyframes movingclouds {
	0% {margin-left: 0%;}
	100% {margin-left: -100%;}
}