.ui-mask {
  position: absolute;
  z-index: 10000;
  background: black;
  background: rgba(0,0,0,.5);
}

.ui-mask-bright {
  background: white;
  background: rgba(255,255,255,.8);
}

.ui-mask-empty {
  width: 16px;
  height: 16px;
  position: absolute;
  top: 50%;
  left: 50%;
  margin: -8px 0 0 -8px;
  background: transparent url(load.gif) no-repeat center;
}

.ui-mask-bright .ui-mask-empty {
  background-image: url(load-bright.gif);
}