Se vuoi lasciare lo spazio per un header in alto, l'immagine non può andare come sfondo del body.
Un esempio usando posizionamenti assoluti e con un header e un footer fissi:
codice:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-15" />
<title>Esempio</title>
<style type="text/css">
html, body{
width: 100%;
height: 100%;
margin:0;
}
#main {
width: 100%;
min-width: 900px;
height: 100%;
position:relative;
}
#header {
position: absolute;
background:green;
left: 0px;
top: 0px;
right: 0px;
height: 28px;
}
#content {
position: absolute;
background:pink;
left: 0px;
top: 30px;
right: 0px;
bottom: 30px;
}
#background {
position: absolute;
left: 0px;
top: 0px;
right: 0px;
bottom: 0px;
z-index:2;
width:100%;
height:100%;
}
#left {
position: absolute;
background:yellow;
top: 0px;
left: 0px;
width: 250px;
bottom: 0px;
z-index:3
}
#right {
position: absolute;
top: 0px;
left: 254px;
right: 0px;
bottom: 0px;overflow:auto;
z-index:3
}
#footer {
position: absolute;
background:red;
height: 28px;
left: 0px;
bottom: 0px;
right: 0px;
}
</style>
</head>
<body>
<div id="main">
<div id="header"></div>
<div id="content">
[img]rabbit.jpg[/img]
<div id="left"></div>
<div id="right"><p style="height:600px">solo per verificare lo scrolling</p> </div>
</div>
<div id="footer"></div>
</div>
</body>
</html>