.button--loading {
  width: 20px;
  height: 20px;
  border: 4px solid rgba(255, 255, 255, 0.25);
  border-top-color: rgba(255, 255, 255, 0.75);
  border-radius: 50%;
  animation: spin 1s ease infinite;
  margin-right: 8px;
}

.button--loading--black {
  width: 20px;
  height: 20px;
  border: 4px solid rgba(255, 255, 255, 0.25);
  border-top-color: rgba(0, 0, 0, 0.75);
  border-radius: 50%;
  animation: spin 1s ease infinite;
  margin-right: 8px;
}

@keyframes spin {
  from {
    transform: rotate(0deg);
  }
  to {
    transform: rotate(360deg);
  }
}