Hey Rafa,
first of all, thank you for the purchase!
you’re right, it’s an issue indeed – the theme’s script only recognizes and replaces images within the normal “img” html tags, not background images. I did add a mechanism to circumvent that for portfolio item backgrounds, yet no such fix exists for the icon menu yet. It will require some programmatic changes to the theme, but so far here’s an easy fix you can try to implement:
1). make the icon menu images twice as large as you need them to be on normal (non-retina) displays; make sure that the image files are of the same dimensions each (ideally – squares).
2). upload these images to the respective icon menu items in the “Icon Menu” tab of the theme options panel;
3). apply this CSS (you can add it inside the “Style: Add Custom CSS” tab of the theme options panel:
#iconmenu .icons-item { background-size: 50%; }
You can adjust the background-size figure until the icons are of the size you want on the non-retina displays (as long as it is less than 50%).
Sincerely,
Andrii / Satori Studio