.item {padding:15px}
.column {float: left;}
.size-1of4 {width: 25%;}
.size-1of3 {width: 33.333%;}
.size-1of2 {width: 50%;}

/* Configurate salvattore with media queries */
@media screen and (max-width: 767px) {
    #timeline[data-columns]::before {
        content: '1 .column';
    }
}


@media screen and (min-width: 768px) and (max-width: 991px) {
    #timeline[data-columns]::before {
        content: '2 .column.size-1of2';
    }
}

@media screen and (min-width: 992px) {
    #timeline[data-columns]::before {
        content: '3 .column.size-1of3';
    }
}