refactor: unify card no-data face and fluid sizing

Extract card.notice so every cached card's no-data state is one fluid,
theme-consistent face instead of a copy per widget, and delete the
fixed-size card.label it replaces.

Derive weather's arc geometry from its band (pad, curve room, sun dot,
time labels) instead of fixed pixels, and cap the arc at a proportion of
the card's width rather than 240px.

Derive disks' bar-fallback height and its address type from the card's
own label scale.

Standardise the big-value factor to 1.0 across the fit_unit cards and
document the big-value colour rule and the disks headline exception.

1 files changed, 7 insertions, 1 deletions

diff --git a/DESIGN.md b/DESIGN.md
index 2249fac..34e8d95 100644
--- a/DESIGN.md
+++ b/DESIGN.md
@@ -11,7 +11,9 @@ bottom:
 
 - **Header.** The title, or the glyph that stands in for it, sits top-left in
   the `label` colour. The card's **big number** sits at the right edge, on the
-  same line, in `FONT_HEAVY`. Nothing else shares that line.
+  same line, in `FONT_HEAVY`. Nothing else shares that line. A card whose data
+  lives entirely in its variable band drops the big number: `disks` has no
+  headline, the rings are the value.
 - **Body.** Rows follow one pattern: **label left, value right**
   (`card.text` and `card.text_right`), so the eye runs down the right edge for
   numbers. A row's value takes the `threshold` colour when it is a measured
@@ -62,6 +64,10 @@ One language for every measured quantity, so state is read rather than decoded:
   widget.
 - `warning` is the palette's middle role. The board should show all three
   states in normal use, or the language is not earning its place.
+- The big value's colour follows what it is: `body` for a plain number, the
+  threshold roles when it is a measured quantity, the phase's own role in
+  `breaktimer`, and `heading` when it names rather than measures (the calendar
+  month).
 
 ## Glyphs