/* ----------container zentriert das layout-------------- */
#container {
width: 800px;
margin-bottom: 10px;
margin-left: auto;
margin-right: auto;
/*background-color: #EBD3E0;*/
background-color: #b0c4de;
}

/* ----------banner for logo-------------- */
#banner {
background-color: #DEDEDE;
text-align: right;
padding: 0px;
margin: 0px;
}
#banner img {padding:10px 0px;} 

#banner a:link {
    color:#ffffff;
    text-decoration:none;
}

#banner a:visited { 
    color:#ffffff;
    text-decoration:none;
}

/* -----------------Inhalt--------------------- */
#content {
background-color: #ffffff;
padding: 0px;
margin-left: 200px;
margin-right: 0px;
}
div#content { 
min-height:600px;
height:expression(this.scrollHeight > 600 ? "auto":"600px"); 
}

p, pre{
padding: 5px 10px;
margin:0px;
}

/* --------------left navigavtion------------- */
#left {
float: left;
width: 200px;
margin: 0px;
padding: 0px;
}

/* -----------footer--------------------------- */
#footer {
clear: both;
margin: 0px;
padding: 0px;
text-align: right; 
}
#left a { 
    display:block;
    width:120px;
    border:4px #99d;
    margin-top:4px;
    padding:6px;
    font-family:Arial, Verdana, sans-serif;
    font-size:120%;
    font-weight:bold;
}

#left a:link {
    color:#225378;
    text-decoration:none;
}

#left a:visited { 
    color:#225378;
    text-decoration:none;
}

#left a:hover {
    color:#ffffff;
    background-color:#225378;
    text-decoration:none;
}

#left a:active {
    color:#ffffff;
    background-color:#225378;
    text-decoration:none;
}

#left a.aktiv {
    color:#ffffff;
    background-color:#225378;
    text-decoration:none;
}

[...]
<div id="container">
    <div id="banner" ><img src="logo.jpg" alt="logo" width="414" />
         [...]
    </div>
    <div id="left">
        <a class="aktiv" href="#">Link1</a>
        <a href="sem.html">Link2</a>
        <a href="adwords.html">Link3</a>
        <a href="analytics.html">Link4</a>
        <a href="leistungen.html">Link5</a>
        <a href="preise.html">Link6</a>
        <a href="wir.html">Link7</a>
        <a href="glossar.html">Link8</a>
    </div>
    <div id="content">
        [...]
    </div>
     <div id="footer">
         [...]
     </div>
</div>
[...]

#left {
float: left;
width: 200px;
padding: 0px;
margin-left: auto;
margin-right: auto;
}

#left {
float: left;
width: 200px;
padding: 0px;
margin: 0px;
text-align: center;
}

#left a { 
    display:block;
    width:120px;
    border:4px #99d;
    margin-top:4px;
    padding:6px;
    font-family:Arial, Verdana, sans-serif;
    font-size:120%;
    font-weight:bold;
    text-align: center;
}

<div id="left" align="center">