I don't know if I found a bug or not.
I have a tiled background set to resize to a proportion of the window and be centered.
On my desktop it works perfectly, but when I try android (chrome) it's off center.
exported webpage:
https://www.dropbox.com/s/y57z3b62k0dfx3n/index.html
capx:
https://www.dropbox.com/s/xyyzfte64srhevm/box.capx