I see exactly 2:1 everywhere [0], including road edges. What are you talking about?
It's 2-1-1-2-1-1-2
EDIT: on closer inspection, it is 2:1, but with a weird artifacting. It does a 1x3 segment followed by a 2x3 segment, repeating.
On the game site, the images do follow 2:1 with expected pixel-perfect rendering.
[1] https://camo.githubusercontent.com/bc5894f89d64f4cb8f01e4c02...