If you’re thinking of a side scroller like the original Super Mario, Y is up/down and X is left/right making the new dimention Z being forward/backward.
However if you think of 2D space like the first LoZ, then Y is North/South and X is East/West making Z up/down
It depends on how you view 2D->3D.
If you’re thinking of a side scroller like the original Super Mario, Y is up/down and X is left/right making the new dimention Z being forward/backward.
However if you think of 2D space like the first LoZ, then Y is North/South and X is East/West making Z up/down
Same with CSS for the same reason.