function send_back(id_capa){
    var valor;
    valor = document.getElementById(id_capa).style.zIndex;
    document.getElementById(id_capa).style.zIndex=valor-2;
 }
  function restaurar_zindex(id_capa){
   document.getElementById(id_capa+'2').style.zIndex=1;
   document.getElementById(id_capa).style.zIndex=2;
 }
  function locate_divs(){
    var top_value = document.getElementById('promo_rent_car').style.top;
    var left_value = document.getElementById('promo_rent_car').style.left;
    document.getElementById('promo_rent_car2').style.top=top_value;
    document.getElementById('promo_rent_car2').style.left=left_value;
    left_value = document.getElementById('cost_rent_car').style.left;
    document.getElementById('cost_rent_car2').style.top=top_value;
    document.getElementById('cost_rent_car2').style.left=left_value;
    left_value = document.getElementById('reserv_rent_car').style.left;
    document.getElementById('reserv_rent_car2').style.top=top_value;
    document.getElementById('reserv_rent_car2').style.left=left_value;
    //alert("HI!");
 }