The "area" of a sign shall be construed to include all lettering, wording, and accompanying designs and symbols, together with the background, whether open or enclosed, on which they are displayed, but not including any supporting framework and bracing which is incidental to the display itself. Where the sign consists of individual letters or symbols attached to or printed on a surface, the area shall be considered to be the smallest rectangle which can be drawn to encompass all of the letters and symbols.