function change_text_size(val) {
  var wrapper = document.getElementById('wrapper');
  wrapper.style.fontSize = val+'em';
  document.cookie = "fontSize="+val;
}

function get_cookie() {
  if (document.cookie.length == 0) {
    return "";
  }
  start = document.cookie.indexOf("fontSize=");
  if (start == -1) {
    return "";
  }
  start += 9;
  end   =  document.cookie.length;
  return document.cookie.substring(start,end);
}

function get_default_size() {
  var wrapper = document.getElementById('wrapper');
  var cookieval = get_cookie();
  if (cookieval.length == 0) {
    return;
  }
  wrapper.style.fontSize = cookieval+"em";
}

window.onload = function() {
  get_default_size();
}