> The LibreOffice 5.4 in the daily build came with it. Unlike you, I didn't install it from deb.
Sorry, I don't understand why installing it from .deb should change the behavior
> All themes with a dark header bar do this, unless they are fixed. Like I said, look at what Adapta or United did to correct this.
Adapta seems affected as well to me, it's just less noticeable. If you look at the picture the headerbar's border stops just below the close button on top corner.
> The LibreOffice 5.4 in the daily build came with it. Unlike you, I didn't install it from deb.
Sorry, I don't understand why installing it from .deb should change the behavior
> All themes with a dark header bar do this, unless they are fixed. Like I said, look at what Adapta or United did to correct this.
Adapta seems affected as well to me, it's just less noticeable. If you look at the picture the headerbar's border stops just below the close button on top corner.