This is my first real attempt at any CC3+ map, and I am using Cosmographer 3 to do it. I have lost the map border layer of my current map in Cosmographer 3. I wanted to resize my drawing because I gave myself way too much space, which I did not need. How do I restore my map border layer to resize my drawing?

I don't know what happened, but the star background disappeared at one point, and my attempts to export to jpg result in a tiny pixelated image in the top left corner of the image. I tried to use File > Resize Drawing Area, and I got this message: "Unable to find map border." How do I get my map border back so I can resize my map to the 500 x 500 ft space I actually need, rather than the 50000 x 50000 space I put in?

Is there anyone who can help out? Find my file attached.