.vendor_logos ul {
    display: flex;
    flex-flow: row wrap;
    align-items: center;
    justify-content: space-between;
    position: relative;
    padding: 20px 20%;
}
.vendor_logos ul > li {
    flex: 1;
    list-style-type: none;
    flex-basis: 20%;
    margin: 5px;
    width: 170px;
    height: 70px;
}

.vendor_logos ul > li > img {
    width: 170px;
}