Forum:Background color of effect monsters

Oy, I've always wondered why the orange-brownish background color on effect-monster cards isn't consistent. From what I can tell, the color on some cards seem to be darker than on others even if the cards are of the same rarity. For example, I have two lord poisons in my deck, and the background color on one of those is darker than the other. The darker card is limited edition from gold series 2, but still, my two botanical girl cards seem to have the same color even though one of them is 1st edition and the other unlimited so it doesn't seem like the edition of the card is the only factor in the color discrepancy. Is there any special meaning to this difference in card color? I can't help but be a bit curious about it :p