Here's a fiddle of my solution and the code is below (fixed link)
The advantages to this solution is that when the parent container's size changes, the content container will expand, while retaining it's margins and the right sidebar will always remain on the right.
Hope this helps.
Note In the fiddle, the content
container is a little slim. This is due to the size of the window. Change the size of the window {hover over the dividers, click and drag}, to see the benefits.
<div class="container">
<div class="content">
centered content
</div>
<div class="right">
right
<div>
</div>
.container {
width:100%;
position:relative;
}
.container .content {
width:auto;
margin:0 200px;
background:green;
}
.container .right {
width:200px;
position:absolute;
top:0px;
right:0px;
background:#f00;
}
.content, .right {
height:300px
}