jquery-mobile/css/structure/jquery.mobile.popup.css

.ui-popup-container {
  display: inline-block;
  position: absolute;
  padding: 0px;
}

.ui-popup-screen {
  opacity: 0;
}

.ui-popup-btn-close {
   position:absolute; 
   top:-15px; 
   right:-15px;	
}