Ok, I experimented with your suggestions. One important constraint is that I need a generic solution that works with any text, any font family, any font size and any alignment. Therefore, hard-coded margins won't work. Thus, the simplest solution for now is to use "position: relative" for all but justified text and "position: absolute" for all justified text.
But I would still need some generic solution for the incorrect positioning of the justified text. Would there be any "relative correction" that would work for justified text? (I'm guessing, probably not, since then it might have already been added as functionality to SplitText...?)
Thanks, Pascal