but I can't work out how to add spacing (cell-spacing/margin) between my columns.

I want to have a floaty look to my page elements with the background visible between spaces in columns etc.

many thanks
-rob

I suggest that you put one extra DIV into each table cell (left sidebar, center, right sidebar), then put padding on the table cells or margin on the new DIV's to move them away from each other with space between them where the background can shine through.