.pimcore_nav_fibu_customer {
    background: url(/bundles/pimcoreadmin/img/flat-white-icons/businessman.svg) center center no-repeat !important;
}
.pimcore_nav_fibu_customer_private {
    background: url(/bundles/pimcoreadmin/img/flat-white-icons/person.svg) center center no-repeat !important;
}