it needs to be a single icon, there's no functionality anywhere to pick a different icon based on the theme

so it should work both on light and dark background, and i don't think there's a way around having a border

tbf the original ghost bird design has a a white background but i don't think that helps 😀 :  
https://media.x0f.org/575280eb3a8c453d181fc24c2a3942abd45bf5b355f445030070a06cf941f240.png