#root {
  position: relative;
}

#root:empty {
  position: fixed;
  z-index: 2000;
  top: 50%;
  left: 50%;
  width: 100%;
  height: 100%;
  background: #FFF url(loading.gif) no-repeat center;
  transform: translate(-50%, -50%);
  -webkit-transform: translate(-50%, -50%);
}