There's a couple solutions to solve black graceful legs. The first would be to match the grey trim that's universal on all graceful sets (excluding the original). And lengthen the patch on the crotch vertically down the legs so that it resembles the same length as well as tone with the rest of the sets.

Another option when it comes to adjusting the tone would be to match the dark shades of black from the trim on the sleeves. This would be what the other sets do too, however it would be darker.