Схема коммуникаций между доменами

iframe_inner.html

<script src="http://readmanga.ru/js/jquery/jquery-1.4.3.min.js"></script>
<h2>inner</h2>

<script>
function notify_parent(message) {
  if ('parent' in window && window != window.parent && 'postMessage' in window.parent) {
    window.parent.postMessage(message, '*');
  }
}
jQuery(function() {
  notify_parent('page_change:20');
});
$(window).bind('message', function(e) {
  $(document.body).append('<h2>remote message from '+e.originalEvent.origin+': "'+e.originalEvent.data+'"</h2>');

  var css_match = e.originalEvent.data.match(/^include_stylesheet:(.*)$/);
  if (css_match.length == 2) {
    var tag = document.createElement('link');
    tag.href = css_match[1];
    tag.setAttribute('media', 'screen');
    tag.setAttribute('type', 'text/css');
    tag.setAttribute('rel', 'stylesheet');
    var s = document.getElementsByTagName('script')[0];
    s.parentNode.insertBefore(tag, s);
  }
});
</script>

main.html

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<h2>outer</h2>
<script>
$(window).on('message', function(e, data) {
  $(document.body).append('<h2>remote message from '+e.originalEvent.origin+': "'+e.originalEvent.data+'"</h2>');
});
$(window).load(function() {
  window.frames[0].postMessage('include_stylesheet:http://shikimori.org/assets/common-datauri.css', '*');
});
</script>

<iframe src="http://localhost2:3000/iframe/inner" width="800" height="200">