Hello
i found a naming mistake of the graphiv-files:

king and queen are named the wrong way around.
The king is actually the rounded puffy crown and the queen is the one with the 5 spikes.

That mistake appears in the download from start-post and 2x in the link in the first comment.

I also don´t like, that they have solid white background.
I turned that to transparent in my downloaded copy and also for all the canvas size to 64x64 pixels, what seems to be a nice fitting board-cell-size for them.
So they can be easier used in chess related videogames.