habe ich ausprobiert:
<style type="text/css">
body {
background-color: #878989;
margin:0px;
padding:0px;
}
/* Hauptdivs */
div#headerlinks {
margin: 0;
padding: 0;
width: 5%;
background-color: #585959;
float:left;
margin-right:0;
}
div#headermitte {
margin: 0;
padding: 0;
background-color: #000000;
margin-left:0;
margin-right:0;
}
div#headerrechts {
margin: 0;
padding: 0;
width: 5%;
background-color: #585959;
float: right;
margin-left:0;
}
div.innen {
height: 165px;
}
div#headerstreifen {
margin: 0;
padding: 0;
width: 16px;
height: 165px;
background-color: #434444;
}
</style>
</head>
<body>
<div>
<div id='headerlinks'><div class=innen>LI</div></div>
<div id='headerrechts'><div class=innen><div id='headerstreifen'>RE</div></div></div>
<div id='headermitte'><div class=innen>MI</div></div>
<div style='clear:both'></div>
</div>
</body>