Control of position for Ecwid Product popups?

I try to set up a shop with only 2 products, which works magnificent together with Ecwid. But when I use the “Ecwid-buy-button” a popup appears and the position is somehow odd.
You may have a look at the Testversion at
Carefull, don’t buy anything, as Ecwid doesn#t allow sandbox testing :slight_smile:
Any ideas to control the position??