Left inner div flexible width Left div Left div Left div Left div
Right inner div Right inner div flexible width Right inner div
Left inner div flexible width Left div Left div Left div Left div Left div Left div Left div Left div Left div Left div
This div has no height so it has flexible height and flexible width
Middle div 400px wide has a fixed width.
This div has no height so it has flexible height.
The fluid widths for the side columns work in IE6, IE7, Firefox, Opera, Safari and Google Chrome. This middle div has a fixed 400px width and has no stated height so it has flexible height.
The floated side divs both have width: 50% and a negative side margin next to the center to drag them towards the center and inner divs with a positive side margin to drag them back again. This leaves space in the middle for the middle div which has float: left to display next to the left div. As position:absolute is not used for the content level side and middle divs which have flexible height it allows the bottom-fixed footer below to know where they stop and to allow a scrollbar if necessary to be able to see all of the content level div which has the most height if the viewport resolution isn't enough to show them both.
The footer has position: fixed so that it is tied to the bottom of the viewport (except in IE6).
Right inner div flexible width Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div Right inner div
This div has no height so it has flexible height and flexible width