A white page, and cards that still read on it

The canvas was #F1F0EC — a warm grey that made every screen look slightly
dull. It is white.

── You cannot have both ──

That canvas was not an accident: it was deepened from #F7F6F4 on 2026-09-23
precisely so a white card would sit *on* something and its 1px edge could go
quiet. A white card on a white page has nothing to sit on.

Measured rather than judged by eye: after the canvas change, a pixel scan
across a card boundary on the Orders golden read #FFFFFF from end to end. The
shadow contributed nothing findable. The cards had not become subtle, they had
disappeared.

So the edge comes back. `DmCard` drew its border only for tones that are not
white — the warm canvas was doing that job for the white ones — and now draws
it for every tone, with the lift still underneath. Border plus a soft shadow is
the iOS and Revolut shape rather than the borderless Airbnb one, and that is
the price of a white page. Paid deliberately.

── What moved with it ──

`surfaceAlt` lifts to #F4F2EF. With a white page it is the only token that
makes a surface read as recessed — filled inputs, tiles, skeletons, the sunken
card — so it can no longer sit within a point of the canvas.

`DmCardTone.sunken` filled itself with the canvas colour, which on a white page
is not sunken but invisible. It takes `surfaceAlt`.

lib/ui/tokens.dart

@@ -75,18 +75,34 @@ class DmColors {
   static const ink4 = Color(0xFFB4AEAA);
 
   // ── Surfaces ─────────────────────────────────────────────────────────────
-  /// The page canvas.
+  /// The page canvas. White.
   ///
-  /// Deepened on 2026-09-23. At `#F7F6F4` a white card on it was a 3% step,
-  /// so the 1px border was doing all the separating and every screen read as
-  /// a list of outlined boxes. A canvas the cards can sit *on* is what lets
-  /// the edge go quiet.
-  static const canvas = Color(0xFFF1F0EC);
+  /// ── This has been both, and the trade is real ──
+  ///
+  /// It was `#F7F6F4`, then deepened to `#F1F0EC` on 2026-09-23 so a white
+  /// card would sit *on* something and the 1px edge could go quiet. That
+  /// worked, and it also made every screen read as slightly dull — which is
+  /// the note that brought it here.
+  ///
+  /// You cannot have a white page and borderless cards: one of them has to do
+  /// the separating. On white, [DmCard] is held by its border and
+  /// [DmShadow.card] rather than by contrast, which is the iOS and Revolut
+  /// shape rather than the Airbnb one. That is the choice, made deliberately.
+  ///
+  /// Everything that needs to read as *recessed* — filled inputs, the
+  /// segmented groove, a sunken card — moved to [surfaceAlt] and [groove],
+  /// which are the only tokens still darker than the page.
+  static const canvas = Color(0xFFFFFFFF);
   static const surface = Color(0xFFFFFFFF);
 
-  /// Filled inputs, quiet chips, tiles, skeleton bases. Also the "sunken"
-  /// treatment for a disabled primary action.
-  static const surfaceAlt = Color(0xFFF1EFEC);
+  /// Filled inputs, quiet chips, tiles, skeleton bases, the "sunken" card and
+  /// the sunken treatment for a disabled primary action.
+  ///
+  /// With a white canvas this is the *only* thing that makes a surface read as
+  /// recessed, so it carries more weight than it used to. It was within a
+  /// point of the old canvas, which is why the groove below had to exist at
+  /// all; on white it does its own job again.
+  static const surfaceAlt = Color(0xFFF4F2EF);
 
   /// The bed a segmented control's chosen segment is raised out of.
   ///