there's an overlap there....and it's by design
so that any water that does get behind there can get out
although I'm not convinced it's necessarily a good design in this case...
Looks like I have the exact same shower liner.
I wouldn't worry if it's aligned well and looks nice but mine was a bit more open that I'd like and so I caulked with my favorite laytex caulk just to prevent splashing up inside there. Did it many years ago and as far as I know there's problems form it. I'm also quite comfortable that there would be no issue if I had left it open.
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