function change_size(whatstyle) {	
	 document.getElementById('button_small').src="img/small.jpg";
	 document.getElementById('button_medium').src="img/medium.jpg";
	 document.getElementById('button_large').src="img/large.jpg";
	 document.getElementById('current_style').href="zbl_fonts_"+whatstyle+".css";
	// alert(document.getElementById('current_style').href);
	 set_size_button(whatstyle);
}

function set_size_button(new_style) {
 	document.getElementById('button_'+new_style).src="img/"+new_style+"_1.jpg";
}