.slider {
	width: 200px;
	margin: auto;
	overflow: hidden;
}

.slider ul {
	display: flex;
	padding: 0;
	width: 400%;
	
	animation: cambio 20s infinite alternate linear;
}

.slider li {
	width: 400px;
	list-style: none;
}

.slider img {
	width: 400px;
}

@keyframes cambio {
	0% {margin-left: 0;}
	20% {margin-left: 0;}
	
	25% {margin-left: -100%;}
	45% {margin-left: -100%;}
	
	50% {margin-left: -200%;}
	70% {margin-left: -200%;}
	
	75% {margin-left: -300%;}
	100% {margin-left: -300%;}
}