Revert the last two glass iterations

The colourful blob wash (92fe685) and the flat "straight ice" pass
(5d05592) both missed. Reverting both to get back to the icon-driven
navy palette before rebuilding the look as a proper frosted ice glass
design.

README.md

@@ -112,11 +112,10 @@ no database, no data leaving your machine except the requests you send to Ollama
   list with per-folder counts, Settings/Dark mode pinned to the bottom). It **collapses** to a 68px
   icon rail (remembered in `localStorage`) and becomes a slide-in **drawer** behind a hamburger on
   phones; mobile also keeps the frosted header + iOS tab bar
-- **One palette pulled from the app icon, both themes**: light page `#eef3fa` (pale ice) /
-  sidebar and cards frosted white / border `#dce4f1`; dark page `#121a2c` / sidebar `#0c1322` /
-  surfaces `#1a2337` / border `rgba(255,255,255,.1)`. Surfaces are frosted glass — translucent with
-  `backdrop-blur`, a bright 1px edge and a light-from-above sheen — over a flat backdrop with a
-  single faint highlight.
+- **One navy palette pulled from the app icon, both themes**: light page `#f4f7fd` / sidebar
+  `#e9eff9` / border `#dce4f1`; dark page `#0e1424` / sidebar `#0a0f1c` / surfaces `#171f33` /
+  border `rgba(255,255,255,.12)`. Surfaces are frosted glass (translucent + `backdrop-blur`) over
+  the icon's navy backdrop.
   Text tiers are documented AA ratios (see below), and the cards fill the row with
   `repeat(auto-fill, minmax(280px, 1fr))` — no stranded cards, no dead space
 - Deck cards: title → muted metadata → neutral tags (difficulty carries the only colour:
@@ -728,11 +727,10 @@ Things I chose while building, with the reasoning:
     have no `folderId`), deleting a folder re-homes its decks instead of deleting them, and folder
     names travel in exports so an imported deck lands where it came from. 13 browser checks cover
     create → freeze → move → rename → delete → reload → import.
-18. **The visual language is frosted ice, with restraint.** The icon's blue is the one accent
-    colour driving buttons and highlights; the backdrop is flat with a single faint top highlight,
-    and surfaces — sidebar, cards, chrome, sheets — are translucent glass with a bright edge and a
-    soft sheen. Colour appears in activity tints and semantic feedback only — pretty, but still
-    readable and quiet.
+18. **The visual language is glassmorphism, with restraint.** The icon's blue is the one accent
+    colour driving buttons and highlights; the backdrop is a navy wash; surfaces — sidebar, cards,
+    chrome, sheets — are frosted and translucent. Colour appears in activity tints and semantic
+    feedback only — pretty, but still readable and quiet.
 19. **Custom CSS lives in `@layer components`, and glass uses Tailwind's backdrop utilities.**
     Two build-level traps, both found by looking at real screenshots: unlayered rules beat Tailwind
     utilities (which silently broke `fixed` on the feed), and a hand-written `backdrop-filter` gets
@@ -752,11 +750,10 @@ Things I chose while building, with the reasoning:
     pill CTAs, 18px radii and restrained shadows; the sidebar, cards and chrome are translucent
     glass over the backdrop. Deck cards got real hierarchy: title → muted metadata → tags → summary
     → secondary Study CTA, with secondary actions behind a quiet menu.
-23. **One fixed backdrop layer, deliberately almost flat.** The decorative wash used to be
+23. **One fixed backdrop layer instead of per-page blobs.** The decorative wash used to be
     rendered inside the content column, so on wide screens it was clipped into a visible hard edge.
-    It now lives in a single `position: fixed` layer (`.app-backdrop`, `z-index: -10`): a flat ice
-    or navy base plus one faint highlight at the top — just enough for the glass to catch, without
-    turning into a gradient soup. `body`'s colour matches it so mobile overscroll shows no seam.
+    It now lives in a single `position: fixed` layer (`.app-backdrop`, `z-index: -10`) in the
+    icon's navy and blue, and `body`'s colour matches its bottom so mobile overscroll shows no seam.
 24. **The UI was deliberately made quieter.** One accent colour (`accent-*`), a desaturated
     `frost-*` scale, hairline borders and flat surfaces replaced the saturated gradients and the
     seven-colour activity badges. Semantic colours (green/amber/red) survive only where they carry
@@ -792,8 +789,9 @@ Things I chose while building, with the reasoning:
     Desktop keeps the designed 12–14px field sizes.
 31. **The app icon drives the palette.** The navy rounded-square artwork in
     `assets/app-icon-source.jpeg` is the source of truth: `frost-*` is navy-tinted, the accent is
-    the snowflake blue, the primary CTA is the icon blue (deep in light mode, bright in dark), and
-    every icon/splash/favicon is rendered from it by `scripts/make-icons.mjs`. The sidebar, header, key gate, empty state and install sheet all show
+    the snowflake blue, the backdrop is the same navy wash, the primary CTA is the icon blue (deep
+    in light mode, bright in dark), and every icon/splash/favicon is rendered from it by
+    `scripts/make-icons.mjs`. The sidebar, header, key gate, empty state and install sheet all show
     the real artwork instead of the old monochrome snowflake tile.
 14. **`gpt-oss:120b` does all content work — but it cannot read images** (`this model does not
     support image input`), so `VISION_MODEL` has to stay a multimodal model (`gemma4:31b-cloud`).