.button.is-busy {
  cursor: wait;
  opacity: .72;
}

.button:disabled:not(.is-busy) {
  cursor: not-allowed;
  opacity: .62;
}

.button.is-busy::after {
  content: "";
  display: inline-block;
  width: .8em;
  height: .8em;
  margin-left: .55em;
  border: 2px solid currentColor;
  border-right-color: transparent;
  border-radius: 50%;
  animation: bringall-spin .7s linear infinite;
}

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