GFX-Sector - HTML, CSS

<div class="content">
<div class="content_left">
<img src="img/side_content/login.png" />
<div class="content_left_main">
<?php include("site/sidebar/login.php"); ?>
</div>
<img src="img/side_content/shoutbox.png" />
<div class="content_left_main">
<?php include("site/sidebar/shoutbox.php"); ?>
</div>
<center><a id="224821" href="http://www.gratis-kontaktformular.de">Kontaktformular Generator Php</a><script type="text/javascript" language="JavaScript" src="http://www.gratis-kontaktformular.de/kjsdfijsd.php?drgdgsdsf=224821&ht
h3sfhdh=2"></script></center>
</div>
<div class="content_middle">
<img src="img/main_content.png" />
<div class="content_middle_text">
<?php
switch($_GET['site'])
{
case 'news': include "site/home/news.php"; break;
case 'about_me': include "site/home/about_me.php"; break;
case 'downloads': include "site/downloads.php"; break;
case 'contact': include "site/contact.php"; break;
case 'imprint': include "site/imprint.php"; break;
case 'gallery': include "site/gallery.php"; break;
default: header("Location:index.php?site=news");
}
?>
</div>

</div>
<div class="content_right">
<img src="img/side_content/vodd.png" />
<div class="content_right_main">
<?php include("site/sidebar/vodd.php"); ?>
</div>
<img src="img/side_content/random_pic.png" />
<div class="content_right_main">
<?php include("site/sidebar/random_pic.php"); ?>
</div>
<img src="img/side_content/partner.png" />
<div class="content_right_main">
<?php include("site/sidebar/partners.php"); ?>
</div>
</div>
</div>

/* INHALT DEFINITIONEN */
div.content{
background-color: #ccc;
font-family: Arial;
font-size: 11pt;
border: 1px #fff solid;
border-radius: 10px;
width: 1160px;
height: 1200px;
margin-top: 10px;
margin-bottom: 10px;
padding: 30px 15px 15px 15px;
}
/* INHALT LINKS */
div.content_left{
width: 225px;
float: left;
}
div.content_left_main{
background-color: #696969;
border-bottom-left-radius: 10px;
border-bottom-right-radius: 10px;
margin-bottom: 10px;
padding: 5px;
}
/* INHALT MITTE */
div.content_middle{
background-color: #696969;
color: #292929;
border-radius: 10px;
width: 700px;
margin-left: 5px;
margin-right: 5px;
float: left;
}
div.content_middle_text{
padding: 5px;
}
/* IHALT RECHTS */
div.content_right{
margin: 0;
width: 225px;
float: right;
}
div.content_right_main{
background-color: #696969;
border-bottom-left-radius: 10px;
border-bottom-right-radius: 10px;
width: 215px;
margin-bottom: 10px;
padding: 5px;
float: right;
}