function WriteCookie(key, value, days) {  

   var str = key + "=" + escape(value) + ";";  

   if (days != 0) {  

      var dt = new Date();  

      dt.setDate(dt.getDate() + days);  

      str += "expires=" + dt.toGMTString() + ";";  

   }  

   document.cookie = str;  

}  

function ReadCookie(key) {  

   var sCookie = document.cookie;  

   var aData = sCookie.split(";");  

   var oExp = new RegExp(" ", "g");  

   key = key.replace(oExp, "");  

   

   var i = 0;  

   while (aData[i]) {  

      var aWord = aData[i].split("=");  

      aWord[0] = aWord[0].replace(oExp, "");  

      if (key == aWord[0]) return unescape(aWord[1]);  

      if (++i >= aData.length) break;  

   }  

   return "";  

}  

function DeleteCookie(key)   

{  

   var dt = new Date();  

   var str = key + "=;expires=" + dt.toGMTString();  

   document.cookie = str;  

}  

   

//ユーザー設定項目  

var defSize = 75; //規定サイズ  

var Unit = '%'       //単位  

var chWidth = 5;  //増減幅  

var days = 30;     //クッキー保存日数  

//設定項目終わり  

   

var x = defSize;  

function SetFontSize(v)  {  

   if (v > 10 && v < 300) {   

      document.body.style.fontSize = v + Unit;  

      if (defSize == v)  

         DeleteCookie('FontSize');  

      else 

         WriteCookie('FontSize', v, days);  

      x = v;  

   }  

}  

function FontSizeChange(cv) {  

   if (cv == 0)  

      SetFontSize(defSize);  

   else 

      SetFontSize(x + cv);  

}  

function ReadFontSize() {  

   fs = ReadCookie('FontSize')  

   if (fs != '') SetFontSize(fs);  

}