I tried your solution Ashley , but it doesn't seem to work.
Here is what I added into my code:
I also manually changed the index.html after export to specify that the background should be white.
And here's the result in the simulator in Xcode
As a point of comparison, here is the desired result, the one I'm getting when exporting the Xcode project directly from C3:
As you can see, not only the background on the side is black instead of white, but on the C2 version the height of the layout is smaller. In the C3 version, the black horizontal bar (home bar) is inside the layout, while in the C2 version, it is below the layout. Maybe that's a hint about what's wrong?
Thanks again for your help and if I'm doing something wrong, it would be nice to tell me what I should change to make it work in C2 like in the version exported from C3.