What is the size of the round watch? Is it 218 x 218? Because of the round overlay "round_watch.png" it looks like it is 216 x 216. If you make a screen capture the picture size is 218 x 218.
And how do we know which pixels you can not see on the physical device?
PS in the picture "round_watch.png" there seems something in the display area. It is very noticeable when the background is black.
Best regards,
Antoine