#ajax-loader {
  position: fixed;
  display: table;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}

#ajax-loader > div {
  display: table-cell;
  width: 100%;
  height: 100%;
  vertical-align: middle;
  text-align: center;
  background-color: #000000;
  opacity: 0.65;
}