if (document.images) {
  var menu_home_off = new Image;
  var menu_home_on  = new Image;
  menu_home_off.src = 'img/menu_home_off.gif';
  menu_home_on.src = 'img/menu_home_on.gif';

  var menu_product_off = new Image;
  var menu_product_on  = new Image;
  menu_product_off.src = 'img/menu_products_off.gif';
  menu_product_on.src = 'img/menu_products_on.gif';

  var menu_benefit_off = new Image;
  var menu_benefit_on  = new Image;
  menu_benefit_off.src = 'img/menu_benefits_off.gif';
  menu_benefit_on.src = 'img/menu_benefits_on.gif';

  var menu_app_off = new Image;
  var menu_app_on  = new Image;
  menu_app_off.src = 'img/menu_app_off.gif';
  menu_app_on.src = 'img/menu_app_on.gif';

  var menu_res_off = new Image;
  var menu_res_on  = new Image;
  menu_res_off.src = 'img/menu_res_off.gif';
  menu_res_on.src = 'img/menu_res_on.gif';

  var menu_contact_off = new Image;
  var menu_contact_on  = new Image;
  menu_contact_off.src = 'img/menu_contact_off.gif';
  menu_contact_on.src = 'img/menu_contact_on.gif';

  var sub_menu_stype_off = new Image;
  var sub_menu_stype_on  = new Image;
  sub_menu_stype_off.src = 'img/s-type_off.gif';
  sub_menu_stype_on.src = 'img/s-type_on.gif';

  var sub_menu_mtype_off = new Image;
  var sub_menu_mtype_on  = new Image;
  sub_menu_mtype_off.src = 'img/m-type_off.gif';
  sub_menu_mtype_on.src = 'img/m-type_on.gif';

  var sub_menu_ettype_off = new Image;
  var sub_menu_ettype_on  = new Image;
  sub_menu_ettype_off.src = 'img/et-type_off.gif';
  sub_menu_ettype_on.src = 'img/et-type_on.gif';

  var sub_menu_ctype_off = new Image;
  var sub_menu_ctype_on  = new Image;
  sub_menu_ctype_off.src = 'img/c-type_off.gif';
  sub_menu_ctype_on.src = 'img/c-type_on.gif';
}