After much fussing about the frame, my Mario cross stitch is finished! I think it turned out quite well. I was thinking of putting a black matte around it over the fabric, but the fabric is a little stretched so it didn't quite work. Instead I just folded under the white canvas, taped it to the black paper that is now behind it and put the whole ensemble in an 8x10 frame.
You can still tell that it's not quite square, but it looks much better than having a square matte around it. That only drew attention to its little lopsidedness since you could see some of the white canvas in some spaces.
I had originally purchased a floating frame for the project, but I'm glad I went with just a basic 8x10 instead. The space around the cross stitch isn't all the same, but it's even on the sides and on the bottom. So, I'm happy with it. If you'd like the pattern, please just ask. I think I posted a picture of it in my sneak peek, but it's much easier to see from the original excel document. Anyway, happy crafting! :)