.mfp-image-holder .mfp-close,
.mfp-iframe-holder .mfp-close{
  background: #fed805; // same as popup-content.css background
  border-radius: 50px;
}
.mfp-close, .mfp-close {
  opacity: 1;
  color: black;
}
.mfp-close:hover, .mfp-close:focus {
  color:black;
}