#book_loader_container {
  position: fixed;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
  z-index: 2;
  background-color: rgb(237, 241, 241);

  display: flex;
  align-items: center;
  justify-content: center;
}

#book_loader {
  border: 2vmin solid #ccc;
  border-radius: 50%;
  border-top: 2vmin solid #0665A2;
  width:  12vmin;
  height: 12vmin;
  animation: spin 2s linear infinite;
}
@keyframes spin {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}