function MM_jumpMenu(targ,selObj,restore){ //v3.0
  eval(targ+".location='"+selObj.options[selObj.selectedIndex].value+"'");
  if (restore) selObj.selectedIndex=0;}
  
  

function clearText(thefield){
if (thefield.defaultValue==thefield.value)
thefield.value = ""
} 

var backgroundSrcs = new Array("img/ran/imagen_home_01.jpg","img/ran/imagen_home_02.jpg","img/ran/imagen_home_03.jpg")

function salta_imagen () {
var bgimage=backgroundSrcs[(Math.round(Math.random()*(backgroundSrcs.length-1)))]
document.getElementById("portada").style.backgroundImage = "url('" + bgimage + "')";
}