ul#partners {
    display: table;
    margin: 0 auto;
    list-style: none;
}

ul#partners li {
    float: left;
    width: 25%;
}

ul#partners li a {
    float: left;
    display: block;
}

ul#partners li img {
    display: table;
    margin: 0 auto;
    width: 66%;
}