Lovelace picture elements card not aligned?

Got this card config

Which gives this on the dashboard, you can just see in the first box top left , there is a M button for the monday but the M button is not the same size as the first box in the row. Why - when I created one button in power point, copied the button to create a row of 7 boxes and then copied the same original button to create the buttons for each day , 7 shaded, 7 not shaded, but buttons not same size as boxes??

Yet I created the PNGs in PowerPoint using text boxes all of the same sizes, the row of empty boxes is saved as ss_Matrix,png and the two monday buttons saved as ss_M_On and ss_M_Off.

How come the buttons are not same size as each empty box in the matrix?