Usage
editused to display Sudoku grids. Usage: see internal comments.
ToDo: copy/move caveats from template body to here to minimize updates to body..
Caveats
editIf cells are empty, their (subgrid) borders don't show. Instead you see the table background color. To insulate against this behaviour, the 3x3 table uses background color = grid color.
If all the cells of a box are empty, setting cellsize won't correct subgrid edge disconnects.
When called from Sudoku 9x9 grid, cell values are always set, nbsp is used for blank.