Regarding the issue of black pieces losing their detail, I've sometimes seen (in contexts other than chess) black images with white outlines, so I wonder if it would be possible to reverse the color of the outlines, or even have something like an outlineColor variable? (Or perhaps blackOutline and whiteOutline.) It's something that probably would only work on SVG sets, but it's a thought.
Regarding the issue of black pieces losing their detail, I've sometimes seen (in contexts other than chess) black images with white outlines, so I wonder if it would be possible to reverse the color of the outlines, or even have something like an outlineColor variable? (Or perhaps blackOutline and whiteOutline.) It's something that probably would only work on SVG sets, but it's a thought.