@keyframes slideShow {
    0%{left:0;}
    20%{left:0%;}
    25%{left:-100%;}
    45%{left:-100%;}
    50%{left:-200%;}
    70%{left:-200%;}
    75%{left:-300%;}
    95%{left:-300%;}
    100%{left:-400%;}
}

#slider {
    overflow: hidden;
}
#slider figure img{
width: 20%;
float: left;
}

#slider {
position: relative;
width: 500%;
margin: 0;
left: 0;
text-align: left;
font-size: 0;
animation: 20s slideShow infinite;
    
}