a.menu-icon-13,
    ul.links li.menu-icon-13 a,
    ul.menu li.menu-icon-13 a {
        background-image: url(https://creative-assembly.s3.eu-west-1.amazonaws.com/s3fs-public/menu_icons/bfa_brands-twitter-square_simple-black_128x128_0.png);
        padding-left:px;
        background-repeat: no-repeat;
        background-position: left center;
    }