.slider{
    width: 100%;
    margin: auto;
    overflow: hidden;
    padding-top: 120px;
}

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

    animation: cambio 15s infinite alternate;
    animation-timing-function: ease-in;
}

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

.slider img{
    width: 100%;
    height: 80%;
}

@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%;}
}