.slider {
	width: 50%;
	margin: auto;
	overflow: hidden;
}

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

.slider li {
	width: 50%;
	list-style: none;
}

.slider img {
	width: 50%;
}

.slider {
	width: 70%;
	margin: auto;
	overflow: hidden;
}

.slider ul {
	display: flex;
	padding: 0;
	width: 300%;
	
animation: cambio 20s infinite alternate linear;
}

.slider li {
	width: 100%;
	list-style: none;
}

.slider img {
	width: 100%;
}

@keyframes cambio {
	0% { transform: translateX(0); }
	100% { transform: translateX(calc(-250px * 7))}
}