#loader {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 99;
  display: flex;
  align-items: center;
  justify-content: center;
}
#loader .spinner {
  border: 5px solid #ccc;
  border-top: 5px solid #007bff;
  border-radius: 50%;
  width: 40px;
  height: 40px;
  animation: spin 0.8s linear infinite;
}
@keyframes spin {
  to { transform: rotate(360deg); }
}