function Cambiar(Sale,Entra){
/*  if ( document.getElementById( Sale ).style.visibility != "hidden" ){
    document.getElementById( Sale ).style.visibility = "hidden";
    document.getElementById( Entra ).style.visibility = "visible";
  }*/
  document.getElementById( Entra ).style.zIndex = "3";
  document.getElementById( Sale ).style.zIndex = "2";
}