I'm web designer and I love simplistic style of lichess.org but I think it's a little bit of lacking colours. More contrast would have been propably more cozy which I think that website is missing a bit. Second thing, if you have already made that kind of a modern chess website I really like, why not to go further and put more simplistic pieces like in Magnus Carlsen app. Optional perhaps and it would be beautiful to have the possibility of setting up colours of the board. But the most I would love to see beautiful, simple, modern pieces.