Okay, so I wasn't really able to produce a satisfactory result. Perhaps I was doing something wrong, but making the dividers semi-transparent didn't look that much different at all from the vanilla game.

In an attempt to make something different anyway, I essentially made the dividers and other elements completely transparent, so the bars look fragmented into segments. Here are some screenshots of how that looks:

https://i.imgur.com/99dS4ge.png
https://i.imgur.com/7aQgGzt.png
https://i.imgur.com/7SjTlw0.png

This probably isn't exactly what you suggested, sorry about that. It's not much, but I thought it was worth sharing so here's a download link anyway:

https://www.dropbox.com/s/i36f27kg63j2zzu/Cleaner%20Health%20Interface%20%28Fragmented%20Ver%29.pak?dl=0

I meant something else. I thought the bars were caused by an overlay. Now it seems like there is only one image for the menu (maybe 2, one for hearts and one for no hearts). I thought you could do something to have the separators between the red be darker than the red, but still not as dark as the border around the health bar.

Thanks for trying to make it happen!