Mondi 100% cotton Casual Skirt Nacy Blue

I'm unsure of the exact size or martial, I bought this skirt a few years ago on thredUp and the tag was completely faded out when I got it. ThredUp had it listed as 100% cotton and a size 40 European/Size 8 USA, but I feel it fits more like a size 6. Length 20" The button is starting to come off but that is the only sign of wear I can find. I couldn't quite get the color to show up right in the pictures, it is a very dark navy blue, and the close-up with the button shows the color best.