Awesome! the "bg" argument completely new to me, thank you, those borders are very anoying. I personally prefer the legend without margins

(legend.background = element_rect(color = NA, fill = "black")

but that´s just preference. Also, I recomend not to use the same word for arguments and objects in the code, is very confusing for people new to the matter (like me) 😅😅.
Thank you for sharing
$wine