uaName = navigator.userAgent;	//ユーザエージェント
appName = navigator.appVersion;	//バージョン
var fontSizeUnit = "px";		//単位
var perOrder = 1;				//変化量
var defaultSize = 13;			//初期値
var MinSize = 10;			//最小値
var MaxSize = 16;			//最大値
var ckName = "_FSize";			//クッキーの名前
var ckDays = 30;				//クッキーの有効期限（日）
var ckPath = "/";				//クッキーのパス
var fsCK = GetCookie(ckName);	//クッキーの値

if ( fsCK == null ) {
	currentSize = defaultSize;
}
else{
	currentSize = Number(fsCK);
}

function fscRef(){
	if (( document.layers )||(( appName.indexOf("Mac",0) != -1 ) && ( uaName.indexOf("MSIE 4.0",0) != -1 ))){
		return false;
	}
	else if( document.body ){
		document.body.style.fontSize = currentSize + fontSizeUnit;
	}
}

function fsc( CMD ){
	if( CMD == "larger" ){
		if ( currentSize < MaxSize ){
			var newSize = Number( currentSize + perOrder );
			SetCookie( ckName , newSize );
		}
		else{
			var newSize=Number(currentSize);
		}
	}

	if( CMD == "smaller" ){
		if ( currentSize > MinSize ){
			var newSize = Number( currentSize - perOrder );
			SetCookie( ckName , newSize );
		}
		else{
			var newSize=Number(currentSize);
		}
	}

	if( CMD == "default" ){
		var newSize = defaultSize;
		DeleteCookie( ckName );
	}

	if( document.layers ){
		window.alert( "申し訳ありません。Netscape Communicator4.x はサポートしていません。" );
		return false;
	}
	else if(( appName.indexOf("Mac",0) != -1 ) && ( uaName.indexOf("MSIE 4.0",0) != -1)){
		window.alert( "Sorry! MacIE4.0 is not supported." );
		return false;
	}
	else{
		currentSize = newSize;
		fscRef();
	}
}

function SetCookie(name,value){
	var dobj = new Date();
	dobj.setTime( dobj.getTime() + ckDays * 24 * 60 * 60 * 1000);
	var expiryDate = dobj.toGMTString();
	document.cookie = name + '=' + escape(value)+ ';expires=' + expiryDate + ';path=' + ckPath;
}

function GetCookie (name){
	var arg  = name + "=";
	var alen = arg.length;
	var clen = document.cookie.length;
	var i = 0;
	while (i < clen){
		var j = i + alen;
		if (document.cookie.substring(i, j) == arg)
			return getCookieVal (j);
		i = document.cookie.indexOf(" ", i) + 1;
		if (i == 0) break;
	}
	return null;
}

function getCookieVal (offset){
	var endstr = document.cookie.indexOf (";", offset);
	if (endstr == -1)
		endstr = document.cookie.length;
	return unescape(document.cookie.substring(offset,endstr));
}

function DeleteCookie(name){
	if (GetCookie(name)) {
		document.cookie = name + '=' +
		'; expires=Thu, 01-Jan-70 00:00:01 GMT;path='+ckPath;
	}
}