I remember seeing it years ago, still amazed by it. What's even cooler is that it was created almost 10 years ago and I believe it hasn't changed much since then. You can read about it [here](https://acko.net/blog/zero-to-sixty-in-one-second/)
From the blog that another reply linked (https://acko.net/blog/zero-to-sixty-in-one-second/)
'Rather than try and emulate some of the bling for CSS 3D-only environments, it's all or nothing. Without WebGL, you get plain images.'
Although this blog post is from 2013, so who knows if this is the actual reason.
Thankfully, the blog post also links to a video so you can still view it:
https://www.youtube.com/watch?v=zjwA1VmuPnw
The iPad does present itself as Mac useragent now, so I think it is deliberately targeting iOS devices and the iPad doesn't match that anymore. Even when I sized the split screen down to a narrow column it still gives me the full version.
And you can scroll up to see it in full 3d!