php – 为什么我没有滚动条？

这是一个链接：test website

我的PHP语法：

<div id="content">
        <div class="wrapper">
            <div id="home" class="alert">
                Welcome to always4free&copy;! To browse the classifieds,you must first either choose a location or have your location detected.
            </div>
            <?php include "res/pages/categories.php"; ?>
        </div>
    </div>
</div>

到底是怎么回事？

编辑：这是我的CSS：

body {
    background-image: url("http://always4free.org/site/images/bg.jpg");
    background-size: cover;
    font-family: "Mouse Memoirs",sans-serif;
}
.wrapper {
    margin: 0 auto;
    width: 850px;
}
#header {
    background: none repeat scroll 0 0 rgba(0,0.5);
    border-bottom: 3px solid green;
    box-shadow: 0 2px 10px #888888;
    height: 50px;
    left: 0;
    position: fixed;
    top: 0;
    width: 100%;
}
#logo {
    color: rgba(255,255,0.7);
    float: left;
    font-family: "Wendy One",sans-serif;
    font-size: 30px;
    line-height: 50px;
    width: 250px;
}
#logo a:hover {
    color: #FFFFFF;
}
#nav {
    float: right;
    line-height: 50px;
    width: 600px;
}
#nav a:first-child {
    margin-left: 0;
}
#nav a:last-child {
    margin-right: 0;
}
#nav a:link,#nav a:visited {
    color: rgba(255,0.9);
    font-family: "Mouse Memoirs",sans-serif;
    letter-spacing: 1px;
    margin-left: 10px;
    margin-right: 10px;
}
#nav a:hover {
    border-bottom: 2px solid #FFFFFF;
    color: #FFFFFF;
    padding-bottom: 1px;
}
#nav a.detect {
    background-color: rgba(255,0.7);
    border: 1px solid rgba(255,0.4);
    border-radius: 2px 2px 2px 2px;
    color: rgba(0,0.7);
    padding: 5px;
}
#nav a.detect:hover {
    color: #000000;
}
#content {
    font-family: "Mouse Memoirs",sans-serif;
    letter-spacing: 1px;
    margin-top: 70px;
}
.page {
    background: none repeat scroll 0 0 rgba(0,0.5);
    border: 1px solid green;
    color: #FFFFFF;
    font-size: 20px;
    padding: 10px;
}
.alert {
    background: none repeat scroll 0 0 #AD2E1D;
    border: 1px solid #911E0F;
    color: white;
    font-size: 20px;
    padding: 10px;
    text-align: center;
}
#categories {
    margin-top: 20px;
}
#categories h2 {
    color: rgba(255,0.7);
    font-family: "Wendy One",sans-serif;
    font-size: 26px;
}
#categories a:link,#categories a:visited {
    background: none repeat scroll 0 0 white;
    color: black;
    padding: 3px;
}
#categories .block {
    line-height: 35px;
}