.spinner {
  display: block;
  width: var(--spinner-size);
  height: var(--spinner-size);
  margin: .5rem auto;
  color: var(--spinner-color);
  text-indent: -99999em;
  border: var(--spinner-stroke-width) solid;
  border-color: currentColor currentColor transparent;
  border-radius: 50%;
  animation: spinner-border .7s linear infinite;
}

@keyframes spinner-border {
  to { transform: rotate(360deg); }
}