There are just 2 properties to change in ordre to make this work the way you want :
#content {
/* width: 100%; */
margin-left: 100px; /* the width of you sidebar.
Since #content is a div, a block-level element
, its width will be automatically 100%
, minus the margins */
background-color: #f00;
}
#inner {
width: 60%;
/* margin-left: 150px; */
margin-left: auto;
margin-right: auto; /* having margin-left & right set to auto will center your div.
you could also use "margin: 0 auto" */
background-color: #888;
height: 1000px;
}
I have updated you JSFiddle example here : http://jsfiddle.net/Uyv6w/5/