.fila {
    display: -ms-flexbox; /* IE10 */
    display: flex;
    -ms-flex-wrap: wrap; /* IE10 */
    flex-wrap: wrap;
    padding: 70px 4px;
	padding-bottom: 8px; /* margen inferior del bloque de imagenes*/
}

/* Create four equal columns that sits next to each other */
.columna {
    -ms-flex: 25%; /* IE10 */
    flex: 25%;
    max-width: 25%;
    padding: 0px 4px;
}

.columna img {
    margin-top: 8px;
    vertical-align: middle;
}

/* Responsive layout - makes a two column-layout instead of four columns */
@media screen and (max-width: 800px) {
    .columna {
        -ms-flex: 50%;
        flex: 50%;
        max-width: 50%;
    }
}

/* Responsive layout - makes the two columns stack on top of each other instead of next to each other */
@media screen and (max-width: 600px) {
    .columna {
        -ms-flex: 100%;
        flex: 100%;
        max-width: 100%;
    }
}