/* 既存のボタンの色・形は保ち、送信中の状態だけを足す。 */
.form-submit__busy {
  cursor: wait;
}
.form-submit__spinner {
  display: inline-block;
  width: 1em;
  height: 1em;
  margin-right: .5em;
  vertical-align: -.1em;
  border: 2px solid currentColor;
  border-right-color: transparent;
  border-radius: 50%;
  animation: form-submit-spin .8s linear infinite;
}
.form-submit__status {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}
@keyframes form-submit-spin {
  to { transform: rotate(360deg); }
}
@media (prefers-reduced-motion: reduce) {
  .form-submit__spinner { animation: none; }
}