function setFontSize(s) 
{
	var size = new Array();
	size[1] = '0.7';
	size[2] = '0.9';
	size[3] = '1.1';
	
	// replace fontsize_img
	var img = document.getElementById('fontsize_img');
	var img_src = img.src;
	img_src = img_src.substr(0, img_src.length-5);
	img.src = img_src+s+'.gif';
	
	// rewrite body font-size
	var el = document.body;
	el.style.fontSize = size[s]+'em';
}