I have nothing to contribute, but I applaud you for putting in some time to give back. It's a more modern look, which is great for new people looking for LinuxCNC.
From what I can see, it is just a landing page, with links to other parts of the server - I don't see why you can't use what you like.
Personally, I'd like to see some consistency across some of the parts, but I think that would be a big ask!
My 10c worth; just a hearty "good on ya, mate"!