.slider{
    width: 65%;
	height: 65%;
    margin: auto;
    overflow: hidden;
}

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

.slider li {
width: 90%;
list-style: none;
}

.silder 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%;}	   
}