function mySetCookie(myCookie,myValue,myDay){
myExp = new Date();
myExp.setTime(myExp.getTime()+(myDay*24*60*60*1000));
myItem = "@" + myCookie + "=" + escape(myValue) + ";";
myExpires = "expires="+myExp.toGMTString();
document.cookie = myItem + myExpires;
}
function myGetCookie(myCookie){
myCookie = "@" + myCookie + "=";
myValue = "";
myStr = document.cookie + ";" ;
myOfst = myStr.indexOf(myCookie);
if (myOfst != -1){
myStart = myOfst + myCookie.length;
myEnd = myStr.indexOf(";" , myStart);
myValue = unescape(myStr.substring(myStart,myEnd));
}
return myValue;
} 


var wall = new Array();

/* 使用する背景画像を好きなだけ記述 */
wall[0] = "http://blog-imgs-43.fc2.com/m/a/p/maplesixdaywonder/2010071420111458a.gif";


var rnd = Math.floor((Math.random() * 100)) % wall.length;
document.write('<style type="text/css">#header { background-image:url(' , wall[rnd] , '); }</style>');