页面加载时定义样式的cookie值

我在用这里的脚本 http://www.quirksmode.org/js/cookies.html 并已成功创建Cookie..它是根据用户对年龄下拉列表的响应设置的。不过,我做任何事情都有困难。如果存在cookie,我想定义一个样式。这是我的大部分剧本。

function createCookie(name,value,days){
    if (days) {
        var date = new Date();
        date.setTime(date.getTime()+(days*24*60*60*1000));
        var expires = "; expires="+date.toGMTString();
    }
    else var expires = "";
    document.cookie = name+"="+value+expires+"; path=/";
}

function readCookie(name) {
    var nameEQ = name + "=";
    var ca = document.cookie.split(';');
    for(var i=0;i < ca.length;i++) {
        var c = ca[i];
        while (c.charAt(0)==' ') c = c.substring(1,c.length);
        if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
    }
    return null;
}

function checkAge(){
    var min_age = 13;
    var year = parseInt(document.forms["emailForm"]["year"].value);
    var month = parseInt(document.forms["emailForm"]["month"].value) - 1;
    var day = parseInt(document.forms["emailForm"]["day"].value);
    var theirDate = new Date((year + min_age), month, day);
    var today = new Date;

    if ( (today.getTime() - theirDate.getTime()) < 0) {
        var el = document.getElementById('emailBox');
        if(el){
            el.className += el.className ? ' youngOne' : 'youngOne';
        }
        document.getElementById('emailBox').innerHTML = "<style type=\"text/css\">.formError {display:none}</style><p>Good Bye</p><p>You must be 13 years of age to sign up.</p>"; 
        createCookie('age','not13',0)
        return false;
    }
    else {
        createCookie('age','over13',0)
        return true;
    };
};

window.onload=function(){
   var x = readCookie('not13');
   if (x)  {    
        document.getElementById('emailBox').innerHTML = "<style type=\"text/css\">.formError {display:none}</style><p>Good Bye</p><p>You must be 13 years of age to sign up.</p>"; 
   }
}

年龄验证有效,cookie已设置….没有错误(来自firebug)。有人知道我做错了什么吗?