Nešto na brzinu:
HTML kôd:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Sample Page</title>
<style type="text/css">
html, body {
margin: 0;
padding: 0;
}
#wrapper {
width: 900px;
margin: 0 auto;
height: 3000px;
}
#content {
width: 610px;
}
aside {
position: fixed;
top: 0;
left: 0;
width: 100%;
}
#sidebar_c {
width: 900px;
margin: 0 auto;
position: relative;
}
#sidebar_cc {
float: right;
margin-top: 120px;
width: 240px;
}
</style>
</head>
<body>
<div id="wrapper">
#wrapper
<div id="content">
#content
</div>
<aside id="sidebar">
<div id="sidebar_c">
<div id="sidebar_cc">
#sidebar
</div>
</div>
</aside>
</div>
</body>
</html>
Testirao sam samo u Chrome.
Ili da korsitiš JavaScript za pozicioniranje fixed elementa u odnosu na poziciju i dimenzije #wrapper elementa.