function euroinox_menu_item($link, $has_children, $menu = '', $in_active_trail = FALSE, $extra_class = NULL) {
  $class = ($menu ? 'expanded' : ($has_children ? 'collapsed' : 'leaf'));
  if (!empty($extra_class)) {
    $class .= ' '. $extra_class;
  }
  if ($in_active_trail) {
    $class .= ' active-trail';
  }
	if ($link['depth'] == 1) { // 1 for first level, 2 for second, etc
	    $class .= ' first-level';  // change first-level to whatever you'd like to be your class, don't forget the space before.
	  }

  return '<li class="'. $class .'">'. $link . $menu ."</li>\n";
}