.slider {
    width: 40%;
    margin: inherit;
   overflow: hidden;
    
 
}

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

.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%; }
}