For the squares in the top row and left column, half of the border on the top or left edges respectively, is hidden due to being drawn outside of the drawing area. This is due to the border half overlapping the square, and the squares being drawn right up against the edge of the drawing area, without leaving room for the full border to be drawn.
For the squares in the top row and left column, half of the border on the top or left edges respectively, is hidden due to being drawn outside of the drawing area. This is due to the border half overlapping the square, and the squares being drawn right up against the edge of the drawing area, without leaving room for the full border to be drawn.
I'm producing a fix.