Pourquoi ma page n'est-elle pas défilable?

J'ai donc fait quelques pages qui utilisent le code CSS suivant:

html { overflow-y: scroll; }
    ul.navbar {
    list-style-type: none;
    position: fixed;
    top: 00px;
    left: 00px;
    width: 200px;
    height: 700px; 

    background-image:url('/images/B_left-background.png');
}

ul.header {
    position: fixed;
    top: -20px;
    left: 240px;
    height: 100px;
    width:700px;
    background-image:url('/images/B_left-top.png');
}

body {

    position: fixed;
    top: 100px;
    left: 300px;

    font-family: Georgia, "Times New Roman",
        Times, serif;

    background-color: #D6E9B4;
}
div.scrollableContainer {
    background: none repeat scroll 0 0 ;
    border: 1px solid #999999;
    height: 400px;
    margin: 40px;
    overflow: auto;
    width: 800px;
}
h1 {font-family: Helvetica, Geneva, Arial,
        SunSans-Regular, sans-serif }
ul.navbar a {text-decoration: none }

a.send{
    color: black;
    background-image:url('/images/send-message-bt.png');
    position:fixed;
    top:200px;
    left:0px;
    height:80px;
    width:290px;
}

a.token{
    color: black;
    background-image:url('/images/token-ID-bt.png');
    position:fixed;
    top:300px;
    left:0px;
    height:80px;
    width:290px;
}

a.history{
    color: black;
    background-image:url('/images/history-bt.png');
    position:fixed;
    top:400px;
    left:0px;
    height:80px;
    width:290px;
}

a.comp{
    background-image:url('/images/competition-bt.png');
    position:fixed;
    top:500px;
    left:0px;
    height:80px;
    width:290px;
}

a.out{
    background-image:url('/images/B_log-out-bt.png');
    position:fixed;
    top:600px;
    left:50px;
    height:60px;
    width:160px;
}