function setInitialFontSize() {
	var objArray = document.getElementsByTagName("body");
	var obj;
	
	obj = objArray.item(0);
	obj.style.fontSize='70%';
}

function changeFontSize(sizeChange) {
	var objArray = document.getElementsByTagName("body");
	var obj = objArray.item(0);
	
	var currentSize = obj.style.fontSize;
	currentSize = parseInt(currentSize);
	currentSize = currentSize + sizeChange;
	
	if (sizeChange == 0) {
		currentSize = 70;
	}
	
	if (currentSize < 50) {
		currentSize = 50;
	} else if (currentSize > 100) {
		currentSize = 100;
	}
	
	currentSize = currentSize + "%";
	
	obj.style.fontSize=currentSize;		
}