Meinst du so?
<html>
<head><title>test</title>
<style type="text/css">
body,html
{
height: 100%;
padding: 0px;
margin: 0px;
}
#aussen
{
width: 50%;
height: 100%;
background-image: url("strip.png");
background-repeat: repeat-y;
background-position: top left;
margin-left: auto;
margin-right: auto;
}
#innen
{
height: 100%;
padding-left: 60px;
padding-right: 60px;
background-image: url("strip.png");
background-repeat: repeat-y;
background-position: top right;
}
</style>
</head>
<body>
<div id="aussen">
<div id="innen">
Die Mitte
</div>
</div>
</body>
</html>