Sideways Tabs and panels loading

HTML

<div id="sliding-panel1">
    Panel 1
</div>

<div id="sliding-panel2">
    Panel 2
</div>

<div id="sliding-panel3">
    Panel 3
</div>

<div id="sliding-panel4">
    Panel 4
</div>


<div id="menu">
<a href="#" class="button1">Tab 1</a>
<a href="#" class="button2">Tab 2</a>
<a href="#" class="button3">Tab 3</a>
<a href="#" class="button4">Tab 4</a>
</div>

CSS

body {
    margin:0 auto;
    padding: 0;
    font-family:helvetica;
}

#menu {-webkit-transform-origin: bottom left; -webkit-transform: rotate(-90deg); position: fixed; top: 650px; left: 38px;}

#sliding-panel1, #sliding-panel2, #sliding-panel3, #sliding-panel4 {
    width: 700px;
    height: 700px;
    margin: 0 0 0 60px;
    position: absolute;
    top:0;
    padding: 10px;
    background: -webkit-gradient(linear, left top, left bottom, from(#d9d9d9), to(#b7b7b7));
    -webkit-border-radius: 0 0 10px 10px;
    bottom: 0;
    display: none;
    border-left: 1px solid #a6a6a6;
    border-top: 1px solid #a6a6a6;
    border-right: 1px solid #a6a6a6;
    -webkit-box-shadow:inset 0 0  1px #f2f2f2;
    color: #151515;
    text-shadow: 1px 1px 1px #fff;
}

.button1, .button2, .button3, .button4{
    display: block;
    margin: 0 0 0 10px;
    background: -webkit-gradient(linear, left top, left bottom, from(#1590b9), to(#0e617c));
    text-decoration:none;
    -webkit-border-radius: 0 0 10px 10px;
    width: 150px;
    text-align: center;
    padding: 10px 0;
    float: left;
    color: #fff;
    text-shadow: 1px 1px 1px #222;
    border-right: 1px solid #0b495d;
    border-left: 1px solid #0b495d;
    border-bottom: 1px solid #0b495d;
    -webkit-box-shadow:inset 0 0 1px #1cb3e5;
}

JavaScript

$(document).ready(function(){
    $('.button1').click(function(){       
        $('#sliding-panel1').slideToggle('fast');
        $('#sliding-panel2').slideUp('fast');
        $('#sliding-panel3').slideUp('fast');
        $('#sliding-panel4').slideUp('fast');
        return false;
    });
    
    $('.button2').click(function(){
        $('#sliding-panel1').slideUp('fast');
        $('#sliding-panel2').slideToggle('fast');
        $('#sliding-panel3').slideUp('fast');
        $('#sliding-panel4').slideUp('fast');
        return false;
    });
    
    $('.button3').click(function(){
        $('#sliding-panel1').slideUp('fast');
        $('#sliding-panel2').slideUp('fast');
        $('#sliding-panel3').slideToggle('fast');
        $('#sliding-panel4').slideUp('fast');
        return false;
    });
    
    $('.button4').click(function(){
        $('#sliding-panel1').slideUp('fast');
        $('#sliding-panel2').slideUp('fast');
        $('#sliding-panel3').slideUp('fast');
        $('#sliding-panel4').slideToggle('fast');
        return false;
    });
    
    
});