.lb-close {
  background: url('http://192.168.56.2/wordpress_rupo/wp-content/themes/mythemedayo/lightbox/images/close.png') center center no-repeat;
  width: 30px;
  height: 30px;
  display: block;
  text-indent: -9999px;
  opacity: 0.8;
}
.lb-close:hover {
  cursor: pointer;
  opacity: 1;
}