Dark mode is becoming increasingly popular in theme design. A common problem for the user is the logo that doesn’t match dark theme (when the light mode is also used).
The best solution is to have a separate logo for light and dark mode - however, this requires changes directly in the theme files.
So, I suggest adding a Secondary logo option in Ghost admin and new {{@site.logo_secondary}} helper.
This would be interesting, and it would be a nice addition. @eddiesigner recently had a fix workaround for me for this exact issue.
Using invert is not a brilliant solution for dark and light version. If we got other options for uploading dark version logo, that will be perfect
It’s a better solution than the current one, though 
I think the best solution is to use an SVG logo and style it with CSS. We do this on Ghost.org - you’ll see that the homepage has a dark header but the pricing page has a light one. Works really well.
Not likely that we’ll add additional logos to settings - would likely add more complexity than utility