if (document.images)  {
ofirmie = new Image
oferty_spec = new Image
kontakt = new Image
top_menu = new Image
ofirmie.src = 'grafika/ofirmie_over.jpg'
oferty_spec.src = 'grafika/oferty_spec_over.jpg'
kontakt.src = 'grafika/kontakt_over.jpg'
top_menu.src = 'grafika/top_menu.jpg'
}  else  {
ofirmie = ""
oferty_spec = ""
kontakt = ""
top_menu = ""
document.topMenu = ""
}