D340 — The dark theme sits on neutral graphite

Decision. The Atlas's dark surfaces are a neutral graphite (--surface-0 #131416 up to --surface-3 #2b2c31, borders #2f3036/#7c7e86) instead of the brand's warm charcoal (#1a1b19…). Everything else in the palette stays the brand's (D232, D233): the sage accent, the Map hues, the severities, the text tones, and the light theme.

Why. The warm charcoal carries a faint olive cast. Under the sage accent and mid-chroma Map hues the whole dark UI read as one muted green block: the colour that should mark a selection, a Map or a state blended into the ground. A ground with no hue of its own leaves all the colour to the things that mean something, and the contrast audit (test/contrast.test.ts) still passes for every pair.

Alternatives rejected. - Changing the accent or the whole palette: the brand's colours were not the problem, their ground was. - A blue-slate ground: a second hue competing with the sage. - A near-black ground with a glow: more contrast than the reading panels need, and a glow is decoration the brand kit avoids.