Cover image in iPad Kindle App

Hello, all,

I have a 1200x1600 cover (in doc as cover.jpg in content.opf meta-cover); fills screen on einks, looks OK on the Fire. But on iPad App, it's smaller, in the center of the screen.

Then, I have a 1058x1600 image, and it fills the screen vertically (in portrait mode) on iPad. Anyone have any ideas? (I tried resizing the original cover to 1058x1411, trying for the narrower width, still small, center of screen.)

By the way, I'm working with the same document, swapping in diff. images, so it's not in the coding or the meta or guide.

Thanks for any tips. I appreciate it.