var size = 0.80;
var factor = 0.95;
var lo = 0.65;
var hi = 1.2;
function sizechange($status) {
  var body = document.getElementsByTagName('body')[0];
  if (size >= lo && $status=='smaller') {
     factor = 0.95;
	 size = size * factor;
  }
  if (size <= hi && $status=='bigger') {
     factor = 1.05;
	 size = size * factor;
  }
  if ($status=='normal'){
  	size = 0.80;
  }
  
  body.style.fontSize = '' + size + 'em';
  return false;
}