I added 1/4 inch flange of yellow fabric between the inner blue and outer striped borders. I saw this on a blog somewhere but I can't remember where now. I actually considered (for about ten seconds) adding piping into this seam. But I didn't have the patience to make and apply it, so I went with the flange.
Check out the mitered corner on my outer border:
I'm so relieved to have this top completed.
Now I just need to find someone around here to quilt it for me!