@keyframes :local(fade-in) {
  from {
    opacity: 0;
  }
}

@-webkit-keyframes :local(fade-out) {
  to {
    opacity: 0;
  }
}

:local(.fadeIn) {
  animation: _colon_local(fade-in) 5s,/* some, :local(comment) */
    _colon_local(fade-out) 1s _colon_local(wrong);
  content: _colon_local(fade-in), wrong, "difficult, :local(wrong)" _colon_local(wrong);
}