diff --git a/.kiro/steering/design-rules.md b/.kiro/steering/design-rules.md
index f20c373..714ae57 100644
--- a/.kiro/steering/design-rules.md
+++ b/.kiro/steering/design-rules.md
@@ -55,6 +55,8 @@
 
 ## Colors
 
+### Dark Mode (Default — Shipped)
+
 | Role | Value |
 |------|-------|
 | Page background | `#0D0E10` |
@@ -68,6 +70,21 @@
 | Text primary | `#E8E6E0` |
 | Text secondary | `#7A7D85` |
 
+### Light Mode (Planned)
+
+| Role | Value |
+|------|-------|
+| Page background | `#F7F6F3` |
+| Card background | `#FFFFFF` |
+| Sidebar background | `#FAF9F7` |
+| Border | `#E8E5DF` |
+| Gold accent | `#C8A434` |
+| Success | `#2ECC71` |
+| Warning | `#E67E22` |
+| Danger | `#E74C3C` |
+| Text primary | `#1A1A1A` |
+| Text secondary | `#6B6560` |
+
 ## State Management
 
 - **No Zustand or other global state library is used.** State is plain React
diff --git a/assets/themes/archnest-default/archnest-default-dark.png b/assets/themes/archnest-default/archnest-default-dark.png
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diff --git a/assets/themes/archnest-default/archnest-default-light.png b/assets/themes/archnest-default/archnest-default-light.png
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diff --git a/assets/settings-custom-bg b/assets/themes/forest/forest-dark.png
similarity index 100%
rename from assets/settings-custom-bg
rename to assets/themes/forest/forest-dark.png
diff --git a/pics/theme2-light-bg.png b/assets/themes/forest/forest-light.png
similarity index 100%
rename from pics/theme2-light-bg.png
rename to assets/themes/forest/forest-light.png
diff --git a/assets/opt1.bg b/assets/themes/geometric/geometric-dark.png
similarity index 100%
rename from assets/opt1.bg
rename to assets/themes/geometric/geometric-dark.png
diff --git a/pics/theme3-light-bg.png b/assets/themes/geometric/geometric-light.png
similarity index 100%
rename from pics/theme3-light-bg.png
rename to assets/themes/geometric/geometric-light.png
diff --git a/design-decisions.md b/design-decisions.md
index 8784412..f6e77d8 100644
--- a/design-decisions.md
+++ b/design-decisions.md
@@ -35,6 +35,8 @@
   which must be kept in sync or the layout clips/gaps.
 
 ### Colors
+
+#### Dark Mode (Default — Shipped)
 | Role | Value |
 |------|-------|
 | Background (page) | `#0D0E10` |
@@ -48,6 +50,72 @@
 | Text (primary) | `#E8E6E0` |
 | Text (secondary) | `#7A7D85` |
 
+#### Light Mode (Planned — Palette Documented)
+| Role | Value |
+|------|-------|
+| Background (page) | `#F7F6F3` (warm off-white) |
+| Background (cards) | `#FFFFFF` (pure white) |
+| Background (sidebar) | `#FAF9F7` (very light warm gray) |
+| Border (cards) | `#E8E5DF` (soft warm border) |
+| Border/accent (hover/active) | `#C8A434` (gold — same as dark) |
+| Success | `#2ECC71` |
+| Warning | `#E67E22` |
+| Danger | `#E74C3C` |
+| Text (primary) | `#1A1A1A` (near-black) |
+| Text (secondary) | `#6B6560` (warm gray) |
+
+Hero banners per mode:
+- Dark: `assets/themes/archnest-default/archnest-default-dark.png` — dark sci-fi cityscape with neon arches
+- Light: `assets/themes/archnest-default/archnest-default-light.png` — luminous white/gold cityscape, bright sky
+
+Geometric/card backgrounds per mode:
+- Dark: textured black slate with angular gold-lit geometric cuts (top-left and bottom-right diagonal slashes with warm gold edge lighting). Dominant colors: near-black slate `#1A1815`, charcoal `#0F0E0C`, gold edge glow `#C8A434` → `#8B6914`.
+- Light: cream marble with matching diagonal geometric cuts and warm gold edge lighting. Dominant colors: warm cream `#F0EDE6`, gold highlights `#C8A434`.
+
+---
+
+### Forest Theme
+
+A second theme with dark and light modes. Same structural layout as the default
+but with a different visual identity — mountainous alien landscapes with amber/gold
+point lights and a massive planet in the sky.
+
+#### Forest — Dark Mode
+
+| Role | Value | Notes |
+|------|-------|-------|
+| Page background | `#080806` | Near-black with warm brown undertone |
+| Card background | `#121210` | Dark charcoal-brown |
+| Sidebar background | `#0A0A08` | Deepest surface |
+| Border | `#1E1C18` | Warm dark border |
+| Accent | `#D4A850` | Warm amber/gold (slightly warmer than default) |
+| Success | `#2ECC71` | |
+| Warning | `#E67E22` | |
+| Danger | `#E74C3C` | |
+| Text primary | `#E8E4DC` | Warm off-white |
+| Text secondary | `#7A7568` | Warm gray-brown |
+
+Hero banner: dark alien mountain landscape with massive planet, amber point lights on a grid floor, warm gold highlights on peaks. Deep blacks with scattered amber/gold sparks.
+Asset: `assets/themes/forest/forest-dark.png`
+
+#### Forest — Light Mode
+
+| Role | Value | Notes |
+|------|-------|-------|
+| Page background | `#F5F2ED` | Warm ivory |
+| Card background | `#FFFFFF` | Pure white |
+| Sidebar background | `#FAF8F4` | Lightest warm tone |
+| Border | `#E5E0D8` | Soft warm border |
+| Accent | `#D4A850` | Same amber/gold as dark mode |
+| Success | `#2ECC71` | |
+| Warning | `#E67E22` | |
+| Danger | `#E74C3C` | |
+| Text primary | `#1A1810` | Warm near-black |
+| Text secondary | `#6B6558` | Warm brown-gray |
+
+Hero banner: luminous white/ivory mountain landscape with massive planet, golden sparkle points on a marble-like floor, peaks dusted in white with gold vein highlights. Ethereal, bright, airy.
+Asset: `assets/themes/forest/forest-light.png`
+
 Tailwind v4 `@theme` custom colors (`text-gold`, `bg-card`, etc.) don't always
 apply reliably — fall back to inline `style={{ color: '#C8A434' }}` when a
 color isn't rendering, and verify visually after changes.
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