.white-popup {
  background: #fff;
  padding: 30px;
  max-width: 800px;
  margin: 20px auto;
  text-align: center;
  border-radius: 10px;
  position:relative;  
}

button.mfp-close {
    background: transparent;
    border: none;
}


@media ( max-width:800px) {
  .white-popup{ margin:20px;

}