If you want to see how a theme looks with inverted colors, you can install a browser extension (like invert colors).
If you want to make a dark / light variant of a color theme this won't be of any help however, because especially the foreground colors simply do not look good if you just invert them.
Sorry, but I'm not going to add this.
If you want to see how a theme looks with inverted colors, you can install a browser extension (like invert colors).
If you want to make a dark / light variant of a color theme this won't be of any help however, because especially the foreground colors simply do not look good if you just invert them.