function getActiveStyleSheet(){
	var i, a;
	
	for (i = 0; (a = document.getElementsByTagName('link')[i]); i++) {
		if (a.getAttribute('rel').indexOf('style') != -1 && a.getAttribute('title') && !a.disabled) {
			return a.getAttribute('title');
		}
	}
	
	return null;
}

function setActiveStyleSheet(title){
	var i, a, main;
	
	for (i = 0; (a = document.getElementsByTagName('link')[i]); i++) {
		if (a.getAttribute('rel').indexOf('style') != -1 && a.getAttribute('title')) {
			a.disabled = true;
			if (a.getAttribute('title') == title) {
				a.disabled = false;
			}
		}
	}
}


function fontSizeUp(){
	active = getActiveStyleSheet();
	

	switch (active) {
			
		case 'font-normal':
			setActiveStyleSheet('font-medium');
			break;
			
		case 'font-medium':
			setActiveStyleSheet('font-large');
			break;
			
		case 'font-normal':
			setActiveStyleSheet('font-normal');
			break;
			
		default:
			setActiveStyleSheet('font-normal');
			break;
	}
}