• Use canvas transform() method instead of computations in 3d.js.
• Rotation on numbers as well.

I have a few suggestions for you ;)

1. use ternary, just to be different
2. the circle is way too close to the title, add at least 20px of padding
3. put the new game button where it's easy to click (maybe under the triangle, still in the circle)
4. consider using the same color palette as 2048, the colors you've chosen right now look pretty bad toghether, some numbers are also hard to read because of that (including the circle)
5. nobody likes crummed space, leave something for the eye to rest, so remove the red lines completely
   and in the end, you don't really need the circle. It doesn't help. Just remove it to get more space and make the triangle a bit bigger