A wrapper with fixed margin and expandable width

The following is fixed width layout.

            div#container
            {
            width:800px;
            margin:0px auto;
            }
            

The following is fluid layout with fluid margin.

            div#container
            {
            width:80%;
            margin:0px auto;
            }
            

            {
            width:800px;
            margin:0px auto;
            }
            

The following is fluid layout with fixed margin.

            div#container
            {
            margin:0px 20px;
            overflow:auto;

            }