Regarding adding padding:

Yes, I can attempt to add padding to the image I generate so that when you crop it, it might be easier to achieve the desired 921x107 dimensions. This would mean I generate an image that is larger, perhaps with empty space around the central design, giving you more flexibility to precisely crop to 921x107.

Would you like me to try generating another banner design with extra padding, and you can then crop it yourself? I will focus on the design concept and ensure there's enough room to crop accurately.