function sfHover() {
	
	
	var sfEls = document.getElementById("menu_principal").getElementsByTagName("li");
	
	var sfHov = document.getElementById("menu_principal").getElementsByTagName("span");
	
	for (var i=0; i<sfEls.length; i++) {
		sfEls[i].onmouseover=function() {
			this.className+=" sfhover";
		}
		sfEls[i].onmouseout=function() {
			this.className=this.className.replace(new RegExp(" sfhover\\b"), "");
			}
		}
		
		for (var i=0; i<sfHov.length; i++) {
		sfHov[i].onmouseover=function() {
			this.className+=" encima";
		}
		sfHov[i].onmouseout=function() {
			this.className=this.className.replace(new RegExp(" encima\\b"), "");
			}
		}
	}
function init(){

	if (navigator.userAgent.indexOf("Firefox")==-1) {
sfHover();
}
	UpdateClock();
}

var clockID = 0;

function UpdateClock() {
   if(clockID) {
      clearTimeout(clockID);
      clockID  = 0;
   }

   var tDate = new Date();

   document.getElementById("hora").innerHTML = "" 
                                   + tDate.getHours() + ":" 
                                   + tDate.getMinutes();
   
   clockID = setTimeout("UpdateClock()", 60000);
}

window.onload=init;