.chart-loader {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  z-index: 10;
  display: none;
}

.spinner {
  width: 32px;
  height: 32px;
  border: 4px solid rgba(0,0,0,0.2);
  border-top-color: #333;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}