Luminous close button

.lum-lightbox-position-helper:before {
    content: '\00d7';
    color: white;
    position: absolute;
    top: 0;
    right: 0;
    z-index: 100;
    font-size: 50px;
    line-height: 32px;
    font-weight: bold;
    cursor: pointer;
}