.slider {
width: 60%;
margin: auto;
overflow: hidden;
}

.slider ul {
display: flex;
padding: 0;
width: 400%;

animation: cambio 30s infinite alternate;

}

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

.slider img {
width: 100%;
}

@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%;}

}