.add_photo {
    display: flex;
    flex-flow: row wrap;
}
.add_photo > div {
    display: flex;
    flex-flow: row wrap;
    width: 24%;
    margin-bottom: 2%;
    margin-right: 1%;
}
.add_photo > div img{
    width: 100%;
    height: auto;
}
.add_photo > div:nth-child(4n) {
    margin-right: 0;
}
.add-photo img {
	max-width:100%;
}
@media screen and (max-width: 425px) {

    .add_photo > div {
        width: 49%;
    }
}
@media screen and (max-width: 325px) {

    .add_photo > div {
        width: 100%;
        margin-right: 0;
    }
}