Looks like there are issues with window ratios that are very different from 1920x1080. On my 13" MacBook, fullscreen puts the window in 1440x900 (ratio of 1.6), which screws up the positioning:

Switching to 1366x768 for the window size fixes the issue (I'm guessing since 1366/768 is ~1.77, which is very close to 1920/1080).

P.S. Thanks for working on this mod and following through on so many improvements, it's been awesome for a long time and glad to see it getting even better!