Very cool! I remember working on an evolutionary algorithm at one point to generate CSS versions of images using random fonts, positions and transforms. The results you've got here are very impressive.
I should also clarify - I'm more of a front-end developer and I'm just using an open source style transfer algorithm from github (with some minor tweaks) on the back end. I can't take much credit for how well the artworks turn out, apart from the factors of UX guiding people to choose good images, and a good set of preset styles.