var min=10;
var max=30;
var def;

function getCookie(c_name)
{
if (document.cookie.length>0)
  {
  c_start=document.cookie.indexOf(c_name + "=");
  if (c_start!=-1)
    { 
    c_start=c_start + c_name.length+1 ;
    c_end=document.cookie.indexOf(";",c_start);
    if (c_end==-1) c_end=document.cookie.length
    return unescape(document.cookie.substring(c_start,c_end));
    } 
  }
return ""
}

function setCookie(c_name,value,expiredays)
{
var exdate=new Date();
exdate.setDate(exdate.getDate()+expiredays);
document.cookie=c_name+ "=" +escape(value)+((expiredays==null) ? "" : "; expires="+exdate.toGMTString());
}

function checkCookie() {
def = getCookie('def');
if (def==null || def=="")
  {
  def = 16;
  setCookie('def',16,7);
  }
   var elem = document.body;
   elem.style.fontSize = def+"px"
}

function increaseFontSize() {
   var elem = document.body;
      if(elem.style.fontSize) {
         var s = parseInt(elem.style.fontSize.replace("px",""));
      } else {
         var s = def;
      }
      if(s < max) {
         s += 1;
      }
      setCookie('def', s,7);
      elem.style.fontSize = s+"px"
}
function decreaseFontSize() {
   var elem = document.body;
      if(elem.style.fontSize) {
         var s = parseInt(elem.style.fontSize.replace("px",""));
      } else {
         var s = def;
      }
      if(s > min) {
         s -= 1;
      }
      setCookie('def', s,7);
      elem.style.fontSize = s+"px"
}
function resetFontSize() {
   var elem = document.body;
   setCookie('def',16,7);
   elem.style.fontSize = 16+"px"
}