diff --git a/src/components/MapView.jsx b/src/components/MapView.jsx
index 0bd2507..6d6b3e9 100644
--- a/src/components/MapView.jsx
+++ b/src/components/MapView.jsx
@@ -2,7 +2,8 @@ import { useEffect, useRef, forwardRef, useImperativeHandle, useState } from 're
 import maplibregl from 'maplibre-gl'
 import 'maplibre-gl/dist/maplibre-gl.css'
 import { Protocol } from 'pmtiles'
-import { layers, namedTheme } from 'protomaps-themes-base'
+import { layers } from 'protomaps-themes-base'
+import { getTheme, getThemeColors, getThemeSprite } from '../themes/registry'
 import { useStore } from '../store'
 import { decodePolyline } from '../utils/decode'
 import { fetchReverse } from '../api'
@@ -12,6 +13,13 @@ import RadialMenu from './RadialMenu'
 import useContextMenu from '../hooks/useContextMenu'
 import toast from 'react-hot-toast'
 
+
+/** Check if current theme is dark based on registry */
+function isCurrentThemeDark() {
+  const themeId = document.documentElement.getAttribute('data-theme') || 'dark'
+  return getTheme(themeId).dark
+}
+
 const ROUTE_SOURCE = 'route-source'
 const BOUNDARY_SOURCE = 'boundary-source'
 const BOUNDARY_LAYER = 'boundary-layer'
@@ -92,7 +100,7 @@ function applyHighlightExpression(map, layerId) {
   storeOriginalPaint(map, layerId)
 
   const orig = originalPaintValues[layerId]
-  const isDark = document.documentElement.getAttribute('data-theme') === 'dark'
+  const isDark = isCurrentThemeDark()
   const accentColor = getComputedStyle(document.documentElement).getPropertyValue('--accent').trim() || '#7a9a6b'
 
   // Hover: darken text slightly, bump halo to full opacity for focus effect
@@ -236,7 +244,7 @@ function clearAllHighlights(map) {
 
 /** Apply improved base label styling for readability (Google Maps style) */
 function applyBaseLabelStyling(map) {
-  const isDark = document.documentElement.getAttribute('data-theme') === 'dark'
+  const isDark = isCurrentThemeDark()
 
   INTERACTIVE_LABEL_LAYERS.forEach(layerId => {
     if (!map.getLayer(layerId)) return
@@ -265,7 +273,7 @@ function buildStyle(themeName) {
   return {
     version: 8,
     glyphs: 'https://protomaps.github.io/basemaps-assets/fonts/{fontstack}/{range}.pbf',
-    sprite: `https://protomaps.github.io/basemaps-assets/sprites/v4/${themeName}`,
+    sprite: getThemeSprite(themeName),
     sources: {
       protomaps: {
         type: 'vector',
@@ -273,7 +281,7 @@ function buildStyle(themeName) {
         attribution,
       },
     },
-    layers: layers('protomaps', namedTheme(themeName), { lang: 'en' }),
+    layers: layers('protomaps', getThemeColors(themeName), { lang: 'en' }),
   }
 }
 
@@ -397,7 +405,7 @@ function addPublicLands(map) {
     }
   }
 
-  const isDark = document.documentElement.getAttribute('data-theme') === 'dark'
+  const isDark = isCurrentThemeDark()
   const opacityMod = isDark ? 0.7 : 1.0
 
   // Fill layer — data-driven color by agency + designation
@@ -541,7 +549,7 @@ function addContours(map) {
     }
   }
 
-  const isDark = document.documentElement.getAttribute('data-theme') === 'dark'
+  const isDark = isCurrentThemeDark()
   const opMod = isDark ? 0.8 : 1.0
 
   // Minor contours (40ft) — visible z11+
@@ -643,7 +651,7 @@ function addContoursTest(map) {
     }
   }
 
-  const isDark = document.documentElement.getAttribute("data-theme") === "dark"
+  const isDark = isCurrentThemeDark()
   const opMod = isDark ? 0.8 : 1.0
 
   // Minor contours (40ft) — blue scheme
@@ -745,7 +753,7 @@ function addContoursTest10ft(map) {
     }
   }
 
-  const isDark = document.documentElement.getAttribute("data-theme") === "dark"
+  const isDark = isCurrentThemeDark()
   const opMod = isDark ? 0.8 : 1.0
 
   // Minor contours (10ft) — green scheme
@@ -848,7 +856,7 @@ function addUsfsTrails(map) {
     }
   }
 
-  const isDark = document.documentElement.getAttribute("data-theme") === "dark"
+  const isDark = isCurrentThemeDark()
 
   // Invisible hit-area layers for easier clicking
   map.addLayer({
@@ -1015,7 +1023,7 @@ function addBlmTrails(map) {
     }
   }
 
-  const isDark = document.documentElement.getAttribute("data-theme") === "dark"
+  const isDark = isCurrentThemeDark()
 
   // Color expression based on route use class - brighter palette
   const colorExpr = [
diff --git a/src/themes/README.md b/src/themes/README.md
new file mode 100644
index 0000000..e110d59
--- /dev/null
+++ b/src/themes/README.md
@@ -0,0 +1,170 @@
+# Navi Theme System
+
+This directory contains the theme registry and reference files for creating custom map themes.
+
+## Files
+
+- **registry.js** - Theme registry with getTheme(), getThemeColors(), getThemeSprite(), themeList()
+- **dark-flavor-reference.json** - Full namedTheme('dark') output for reference
+- **light-flavor-reference.json** - Full namedTheme('light') output for reference
+
+## Creating Custom Themes
+
+Custom themes must provide a complete `colors` object matching the flavor schema from protomaps-themes-base.
+
+### Required Structure
+
+The flavor object has **73 flat color keys** plus **2 nested objects**:
+
+```javascript
+{
+  // === FLAT COLOR KEYS (73 total) ===
+  
+  // Background & earth
+  "background": "#34373d",
+  "earth": "#1f1f1f",
+  
+  // Land use areas
+  "park_a": "#1c2421",
+  "park_b": "#192a24",
+  "hospital": "#252424",
+  "industrial": "#222222",
+  "school": "#262323",
+  "wood_a": "#202121",
+  "wood_b": "#202121",
+  "pedestrian": "#1e1e1e",
+  "scrub_a": "#222323",
+  "scrub_b": "#222323",
+  "glacier": "#1c1c1c",
+  "sand": "#212123",
+  "beach": "#28282a",
+  "aerodrome": "#1e1e1e",
+  "runway": "#333333",
+  "water": "#31353f",
+  "zoo": "#222323",
+  "military": "#242323",
+  "pier": "#333333",
+  "buildings": "#111111",
+  
+  // Tunnels
+  "tunnel_other_casing": "#141414",
+  "tunnel_minor_casing": "#141414",
+  "tunnel_link_casing": "#141414",
+  "tunnel_major_casing": "#141414",
+  "tunnel_highway_casing": "#141414",
+  "tunnel_other": "#292929",
+  "tunnel_minor": "#292929",
+  "tunnel_link": "#292929",
+  "tunnel_major": "#292929",
+  "tunnel_highway": "#292929",
+  
+  // Roads & casings
+  "minor_service_casing": "#1f1f1f",
+  "minor_casing": "#1f1f1f",
+  "link_casing": "#1f1f1f",
+  "major_casing_late": "#1f1f1f",
+  "highway_casing_late": "#1f1f1f",
+  "major_casing_early": "#1f1f1f",
+  "highway_casing_early": "#1f1f1f",
+  "other": "#333333",
+  "minor_service": "#333333",
+  "minor_a": "#3d3d3d",
+  "minor_b": "#333333",
+  "link": "#3d3d3d",
+  "major": "#3d3d3d",
+  "highway": "#474747",
+  "railway": "#000000",
+  "boundaries": "#5b6374",
+  
+  // Bridges
+  "bridges_other_casing": "#2b2b2b",
+  "bridges_minor_casing": "#1f1f1f",
+  "bridges_link_casing": "#1f1f1f",
+  "bridges_major_casing": "#1f1f1f",
+  "bridges_highway_casing": "#1f1f1f",
+  "bridges_other": "#333333",
+  "bridges_minor": "#333333",
+  "bridges_link": "#3d3d3d",
+  "bridges_major": "#3d3d3d",
+  "bridges_highway": "#474747",
+  
+  // Labels
+  "waterway_label": "#717784",
+  "roads_label_minor": "#525252",
+  "roads_label_minor_halo": "#1f1f1f",
+  "roads_label_major": "#666666",
+  "roads_label_major_halo": "#1f1f1f",
+  "ocean_label": "#717784",
+  "peak_label": "#898080",
+  "subplace_label": "#525252",
+  "subplace_label_halo": "#1f1f1f",
+  "city_label": "#7a7a7a",
+  "city_label_halo": "#212121",
+  "state_label": "#3d3d3d",
+  "state_label_halo": "#1f1f1f",
+  "country_label": "#5c5c5c",
+  "address_label": "#525252",
+  "address_label_halo": "#1f1f1f",
+  
+  // === NESTED OBJECTS (REQUIRED) ===
+  
+  // POI icon colors - all 8 keys required
+  "pois": {
+    "blue": "#4299BB",
+    "green": "#30C573",
+    "lapis": "#2B5CEA",
+    "pink": "#EF56BA",
+    "red": "#F2567A",
+    "slategray": "#93939F",
+    "tangerine": "#F19B6E",
+    "turquoise": "#00C3D4"
+  },
+  
+  // Landcover fill colors - all 7 keys required
+  "landcover": {
+    "grassland": "rgba(30, 41, 31, 1)",
+    "barren": "rgba(38, 38, 36, 1)",
+    "urban_area": "rgba(28, 28, 28, 1)",
+    "farmland": "rgba(31, 36, 32, 1)",
+    "glacier": "rgba(43, 43, 43, 1)",
+    "scrub": "rgba(34, 36, 30, 1)",
+    "forest": "rgba(28, 41, 37, 1)"
+  }
+}
+```
+
+### Theme Config
+
+Add custom themes to `registry.js`:
+
+```javascript
+const themes = {
+  // ... existing themes ...
+  
+  'sepia': {
+    id: 'sepia',
+    name: 'Sepia',
+    dark: false,  // Affects overlay styling and sprite fallback
+    colors: {
+      // Full flavor object (all 73 flat keys + pois + landcover)
+    },
+    satellite: {
+      // Optional: raster adjustments for satellite layer
+      opacity: 1.0,
+      brightnessMin: 0,
+      brightnessMax: 1,
+      contrast: 0,
+      saturation: 0,
+      hueRotate: 0,
+    },
+    overlay: null,  // Reserved for future use
+  },
+}
+```
+
+### Important Notes
+
+1. **All keys are required** - protomaps-themes-base expects every key
+2. **Nested objects matter** - `pois` and `landcover` are objects, not flat keys
+3. **Sprite fallback** - Custom themes fall back to dark/light sprite based on `dark` flag
+4. **CSS vars separate** - Map flavor colors are separate from UI CSS custom properties
diff --git a/src/themes/dark-flavor-reference.json b/src/themes/dark-flavor-reference.json
new file mode 100644
index 0000000..27d2180
--- /dev/null
+++ b/src/themes/dark-flavor-reference.json
@@ -0,0 +1,95 @@
+{
+  "background": "#34373d",
+  "earth": "#1f1f1f",
+  "park_a": "#1c2421",
+  "park_b": "#192a24",
+  "hospital": "#252424",
+  "industrial": "#222222",
+  "school": "#262323",
+  "wood_a": "#202121",
+  "wood_b": "#202121",
+  "pedestrian": "#1e1e1e",
+  "scrub_a": "#222323",
+  "scrub_b": "#222323",
+  "glacier": "#1c1c1c",
+  "sand": "#212123",
+  "beach": "#28282a",
+  "aerodrome": "#1e1e1e",
+  "runway": "#333333",
+  "water": "#31353f",
+  "zoo": "#222323",
+  "military": "#242323",
+  "tunnel_other_casing": "#141414",
+  "tunnel_minor_casing": "#141414",
+  "tunnel_link_casing": "#141414",
+  "tunnel_major_casing": "#141414",
+  "tunnel_highway_casing": "#141414",
+  "tunnel_other": "#292929",
+  "tunnel_minor": "#292929",
+  "tunnel_link": "#292929",
+  "tunnel_major": "#292929",
+  "tunnel_highway": "#292929",
+  "pier": "#333333",
+  "buildings": "#111111",
+  "minor_service_casing": "#1f1f1f",
+  "minor_casing": "#1f1f1f",
+  "link_casing": "#1f1f1f",
+  "major_casing_late": "#1f1f1f",
+  "highway_casing_late": "#1f1f1f",
+  "other": "#333333",
+  "minor_service": "#333333",
+  "minor_a": "#3d3d3d",
+  "minor_b": "#333333",
+  "link": "#3d3d3d",
+  "major_casing_early": "#1f1f1f",
+  "major": "#3d3d3d",
+  "highway_casing_early": "#1f1f1f",
+  "highway": "#474747",
+  "railway": "#000000",
+  "boundaries": "#5b6374",
+  "waterway_label": "#717784",
+  "bridges_other_casing": "#2b2b2b",
+  "bridges_minor_casing": "#1f1f1f",
+  "bridges_link_casing": "#1f1f1f",
+  "bridges_major_casing": "#1f1f1f",
+  "bridges_highway_casing": "#1f1f1f",
+  "bridges_other": "#333333",
+  "bridges_minor": "#333333",
+  "bridges_link": "#3d3d3d",
+  "bridges_major": "#3d3d3d",
+  "bridges_highway": "#474747",
+  "roads_label_minor": "#525252",
+  "roads_label_minor_halo": "#1f1f1f",
+  "roads_label_major": "#666666",
+  "roads_label_major_halo": "#1f1f1f",
+  "ocean_label": "#717784",
+  "peak_label": "#898080",
+  "subplace_label": "#525252",
+  "subplace_label_halo": "#1f1f1f",
+  "city_label": "#7a7a7a",
+  "city_label_halo": "#212121",
+  "state_label": "#3d3d3d",
+  "state_label_halo": "#1f1f1f",
+  "country_label": "#5c5c5c",
+  "address_label": "#525252",
+  "address_label_halo": "#1f1f1f",
+  "pois": {
+    "blue": "#4299BB",
+    "green": "#30C573",
+    "lapis": "#2B5CEA",
+    "pink": "#EF56BA",
+    "red": "#F2567A",
+    "slategray": "#93939F",
+    "tangerine": "#F19B6E",
+    "turquoise": "#00C3D4"
+  },
+  "landcover": {
+    "grassland": "rgba(30, 41, 31, 1)",
+    "barren": "rgba(38, 38, 36, 1)",
+    "urban_area": "rgba(28, 28, 28, 1)",
+    "farmland": "rgba(31, 36, 32, 1)",
+    "glacier": "rgba(43, 43, 43, 1)",
+    "scrub": "rgba(34, 36, 30, 1)",
+    "forest": "rgba(28, 41, 37, 1)"
+  }
+}
\ No newline at end of file
diff --git a/src/themes/light-flavor-reference.json b/src/themes/light-flavor-reference.json
new file mode 100644
index 0000000..fdd8bbd
--- /dev/null
+++ b/src/themes/light-flavor-reference.json
@@ -0,0 +1,95 @@
+{
+  "background": "#cccccc",
+  "earth": "#e2dfda",
+  "park_a": "#cfddd5",
+  "park_b": "#9cd3b4",
+  "hospital": "#e4dad9",
+  "industrial": "#d1dde1",
+  "school": "#e4ded7",
+  "wood_a": "#d0ded0",
+  "wood_b": "#a0d9a0",
+  "pedestrian": "#e3e0d4",
+  "scrub_a": "#cedcd7",
+  "scrub_b": "#99d2bb",
+  "glacier": "#e7e7e7",
+  "sand": "#e2e0d7",
+  "beach": "#e8e4d0",
+  "aerodrome": "#dadbdf",
+  "runway": "#e9e9ed",
+  "water": "#80deea",
+  "zoo": "#c6dcdc",
+  "military": "#dcdcdc",
+  "tunnel_other_casing": "#e0e0e0",
+  "tunnel_minor_casing": "#e0e0e0",
+  "tunnel_link_casing": "#e0e0e0",
+  "tunnel_major_casing": "#e0e0e0",
+  "tunnel_highway_casing": "#e0e0e0",
+  "tunnel_other": "#d5d5d5",
+  "tunnel_minor": "#d5d5d5",
+  "tunnel_link": "#d5d5d5",
+  "tunnel_major": "#d5d5d5",
+  "tunnel_highway": "#d5d5d5",
+  "pier": "#e0e0e0",
+  "buildings": "#cccccc",
+  "minor_service_casing": "#e0e0e0",
+  "minor_casing": "#e0e0e0",
+  "link_casing": "#e0e0e0",
+  "major_casing_late": "#e0e0e0",
+  "highway_casing_late": "#e0e0e0",
+  "other": "#ebebeb",
+  "minor_service": "#ebebeb",
+  "minor_a": "#ebebeb",
+  "minor_b": "#ffffff",
+  "link": "#ffffff",
+  "major_casing_early": "#e0e0e0",
+  "major": "#ffffff",
+  "highway_casing_early": "#e0e0e0",
+  "highway": "#ffffff",
+  "railway": "#a7b1b3",
+  "boundaries": "#adadad",
+  "waterway_label": "#ffffff",
+  "bridges_other_casing": "#e0e0e0",
+  "bridges_minor_casing": "#e0e0e0",
+  "bridges_link_casing": "#e0e0e0",
+  "bridges_major_casing": "#e0e0e0",
+  "bridges_highway_casing": "#e0e0e0",
+  "bridges_other": "#ebebeb",
+  "bridges_minor": "#ffffff",
+  "bridges_link": "#ffffff",
+  "bridges_major": "#f5f5f5",
+  "bridges_highway": "#ffffff",
+  "roads_label_minor": "#91888b",
+  "roads_label_minor_halo": "#ffffff",
+  "roads_label_major": "#938a8d",
+  "roads_label_major_halo": "#ffffff",
+  "ocean_label": "#728dd4",
+  "peak_label": "#7e9aa0",
+  "subplace_label": "#8f8f8f",
+  "subplace_label_halo": "#e0e0e0",
+  "city_label": "#5c5c5c",
+  "city_label_halo": "#e0e0e0",
+  "state_label": "#b3b3b3",
+  "state_label_halo": "#e0e0e0",
+  "country_label": "#a3a3a3",
+  "address_label": "#91888b",
+  "address_label_halo": "#ffffff",
+  "pois": {
+    "blue": "#1A8CBD",
+    "green": "#20834D",
+    "lapis": "#315BCF",
+    "pink": "#EF56BA",
+    "red": "#F2567A",
+    "slategray": "#6A5B8F",
+    "tangerine": "#CB6704",
+    "turquoise": "#00C3D4"
+  },
+  "landcover": {
+    "grassland": "rgba(210, 239, 207, 1)",
+    "barren": "rgba(255, 243, 215, 1)",
+    "urban_area": "rgba(230, 230, 230, 1)",
+    "farmland": "rgba(216, 239, 210, 1)",
+    "glacier": "rgba(255, 255, 255, 1)",
+    "scrub": "rgba(234, 239, 210, 1)",
+    "forest": "rgba(196, 231, 210, 1)"
+  }
+}
\ No newline at end of file
diff --git a/src/themes/registry.js b/src/themes/registry.js
new file mode 100644
index 0000000..80741d5
--- /dev/null
+++ b/src/themes/registry.js
@@ -0,0 +1,107 @@
+/**
+ * Theme Registry for Navi
+ * 
+ * Provides a centralized registry for map themes, supporting both built-in
+ * protomaps themes (light/dark) and custom themes with full flavor objects.
+ * 
+ * Theme config structure:
+ *   id: string        - unique identifier (used in store, data-theme attr)
+ *   name: string      - display name for UI
+ *   dark: boolean     - true if dark theme (affects overlay styling, sprite fallback)
+ *   colors: object|null - null for built-in themes, full flavor object for custom
+ *   satellite: object|null - raster adjustments when satellite layer is present
+ *   overlay: object|null   - reserved for future overlay-specific customizations
+ */
+
+import { namedTheme } from 'protomaps-themes-base'
+
+/**
+ * Theme registry - maps theme IDs to theme configurations
+ * 
+ * Built-in themes (light/dark) use colors: null to signal that namedTheme()
+ * should be called at render time. Custom themes provide a full flavor object.
+ */
+const themes = {
+  light: {
+    id: 'light',
+    name: 'Light',
+    dark: false,
+    colors: null,  // Use namedTheme('light')
+    satellite: null,
+    overlay: null,
+  },
+  dark: {
+    id: 'dark',
+    name: 'Dark',
+    dark: true,
+    colors: null,  // Use namedTheme('dark')
+    satellite: null,
+    overlay: null,
+  },
+  // Custom themes go here. Example:
+  // 'midnight': {
+  //   id: 'midnight',
+  //   name: 'Midnight',
+  //   dark: true,
+  //   colors: { /* full flavor object matching dark-flavor-reference.json schema */ },
+  //   satellite: { opacity: 0.8, brightnessMin: 0.1 },
+  //   overlay: null,
+  // },
+}
+
+/**
+ * Get a theme configuration by ID
+ * @param {string} id - Theme ID
+ * @returns {object} Theme config, falls back to 'dark' if not found
+ */
+export function getTheme(id) {
+  return themes[id] || themes.dark
+}
+
+/**
+ * Get the color flavor for a theme
+ * For built-in themes, calls namedTheme(). For custom themes, returns colors directly.
+ * @param {string} id - Theme ID
+ * @returns {object} Flavor object for use with protomaps layers()
+ */
+export function getThemeColors(id) {
+  const theme = getTheme(id)
+  if (theme.colors === null) {
+    // Built-in theme - use namedTheme from protomaps-themes-base
+    return namedTheme(id)
+  }
+  return theme.colors
+}
+
+/**
+ * Get the sprite URL for a theme
+ * Built-in themes use their own sprites. Custom themes fall back to
+ * dark or light sprite based on the theme's dark flag.
+ * @param {string} id - Theme ID
+ * @returns {string} Full sprite URL
+ */
+export function getThemeSprite(id) {
+  const theme = getTheme(id)
+  // Custom themes don't have matching sprites on CDN - fall back based on dark flag
+  const spriteTheme = theme.colors === null ? id : (theme.dark ? 'dark' : 'light')
+  return `https://protomaps.github.io/basemaps-assets/sprites/v4/${spriteTheme}`
+}
+
+/**
+ * Get list of available themes for UI display
+ * @returns {Array<{id: string, name: string, dark: boolean}>}
+ */
+export function themeList() {
+  return Object.values(themes).map(({ id, name, dark }) => ({ id, name, dark }))
+}
+
+/**
+ * Check if a theme ID is valid/registered
+ * @param {string} id - Theme ID to check
+ * @returns {boolean}
+ */
+export function isValidTheme(id) {
+  return id in themes
+}
+
+export default themes