function chgImg(name, url) { //current_txtsize_image
    document.images["middle"].src ="web/image/txt_normal.gif";
    document.images["bigger"].src = "web/image/txt_bigger.gif";
	document.images[name].src = url; 
}

function replace_css(id,url){ //txtsize_css
  if(!document.getElementById) return false;
  var element = document.getElementById(id);
  if(!element || !element.cloneNode) return false;
  var new_node = element.cloneNode(true);
  new_node.href = url;
  element.parentNode.replaceChild(new_node,element);
  return true;
}