function cambia_bg(letra) {
	//alert(letra);
	var aux = 'opcion_' + letra;
	var clase =document.getElementById(aux).className;
	//alert(clase);
	if(clase=="opcion_menu")
	{
		document.getElementById(aux).className = 'opcion_menu_on';
	}
	else
	{
		document.getElementById(aux).className = 'opcion_menu';
	}
}

function regresa_bg(letra) {
	var aux = 'opcion_' + letra;
	var clase =document.getElementById(aux).className;
	//alert(clase);
	if(clase=="opcion_menu")
	{
		document.getElementById(aux).className = 'opcion_menu_on';
	}
	else
	{
		document.getElementById(aux).className = 'opcion_menu';
	}
}

function muestra_seccion(valor) {
	switch(valor)
	{
		case '1':
			var leyenda = 'ABOUT US';
			carga_menu('1');			
		break;
		
		case '2':
			var leyenda = 'TRAINING';
			carga_menu('2');
		break;
				
		case '3':
			var leyenda = 'CAREERS';
			carga_menu('3');
		break;
				
		case '4':
			var leyenda = 'RESOURCES';
			carga_menu('4');
		break;
				
		case '5':
			var leyenda = 'CONTRIBUTE';
			carga_menu('5');
		break;
				
		case '6':
			var leyenda = 'EVENTS';
			carga_menu('6');
		break;
				
		case '7':
			var leyenda = 'REGISTER';
			carga_menu('7');
		break;
				
		case '8':
			var leyenda = 'CONTACT US';
			carga_menu('8');
		break;
	}
	carga_texto_respectivo(valor);
	document.getElementById('div_nombre_seccion').innerHTML = leyenda;
/*
ABOUT US
TRAINING
CAREERS
RESOURCES
CONTRIBUTE
EVENTS
REGISTER
CONTACT US
*/
}

function cambia_lang(valor) {
	alert(valor);
	window.location = 'change_lang.php?lang=' + valor;
}

function salta_seccion(id) {
	window.location = 'index.php?seccion=' + id;
}

<!--
<!--
var pong;
function makeArray(n){
this.length = n;
for (i=1;i<=n;i++){
this[i]=0;
}
return this;
}

// standard date display function with y2k compatibility
function displayDate() {
var this_month = new makeArray(12);
this_month[0]  = "January";
this_month[1]  = "February";
this_month[2]  = "March";
this_month[3]  = "April";
this_month[4]  = "May";
this_month[5]  = "June";
this_month[6]  = "July";
this_month[7]  = "August";
this_month[8]  = "September";
this_month[9]  = "October";
this_month[10] = "November";
this_month[11] = "December";

var this_day_e = new makeArray(7);
this_day_e[0]  = "Sunday";
this_day_e[1]  = "Monday";
this_day_e[2]  = "Tuesday";
this_day_e[3]  = "Wednesday";
this_day_e[4]  = "Thursday";
this_day_e[5]  = "Friday";
this_day_e[6]  = "Saturday";

var today = new Date();
var day   = today.getDate();
var month = today.getMonth();
var year  = today.getYear();
var dia = today.getDay();
if (year < 1000) {
   year += 1900; }
return( "Geneva,  " + this_day_e[dia] + " " + day + " " + this_month[month] + " " + year);
}