var min=8;
var max=18;
function fontResize(num) {
   	var mytags = new Array()
	mytags[0] = document.getElementsByTagName('div');
	mytags[1] = document.getElementsByTagName('a');
	mytags[2] = document.getElementsByTagName('span');
	mytags[3] = document.getElementsByTagName('td');
	x=0;
	while (x<mytags.length){
		tag=mytags[x];
	   for(i=0;i<tag.length;i++) {
		  var s=12;
		  if(tag[i].style.fontSize) { var s = parseInt(tag[i].style.fontSize.replace("px",""));}
		  if((num>0 && s!=max)) { s += num; }
		  if((num<0 && s!=min)) { s += num; }
		  tag[i].style.fontSize = s+"px"
	   }
	   x++;
   }
}