function action_template_header( $theme ) {
  if ( $theme->matched_rule->name == 'display_entry' && isset($theme->post->info->css) ) {
    foreach ( explode(',', $theme->post->info->css) as $css ) {
      Stack::add( 'template_stylesheet', array( URL::get_from_filesystem(__FILE__) . $css, 'screen' ) );
    }
  }
}