#enter-site .modal-dialog .modal-content .modal-header .close.cancel span{
    position: relative;
}

#enter-site .modal-dialog .modal-content .modal-header .close.cancel span:before{
    content: '';
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    background-image: url("/content/dam/commercial-eu/neurology/microsites/multiplechoices-eu/images/close-modal.png");
    background-repeat: no-repeat;
    background-position: center;
}