.curtain {
  position: absolute;
  left: 50%;
  top: 50%;
  width: 8em;
  height: 1em;
  margin: -0.5em 0 0 -4em;
}

/* .curtain {
  width: 48px;
  height: 48px;
  position: absolute;
  left: 50%;
  top: 50%;
  margin: -24px 0 0 -24px;
  background: rgba(0, 0, 0, 0.5);
  display: inline-block;
  border-radius: 50%;
  box-sizing: border-box;
  animation: animloader 1s ease-in infinite;
}

@keyframes animloader {
  0% {
    transform: scale(0);
    opacity: 1;
  }
  100% {
    transform: scale(1);
    opacity: 0;
  }
}  */