diff --git a/src/components/theme-customizer.tsx b/src/components/theme-customizer.tsx
new file mode 100644
index 00000000..e6206cbb
--- /dev/null
+++ b/src/components/theme-customizer.tsx
@@ -0,0 +1,65 @@
+import React from "react"
+import { Button } from "./button"
+import { Dialog } from "./dialog"
+import { Tooltip } from "./tooltip"
+import { ThemeColor, THEME_COLORS_MAP, getCurrentTheme, applyTheme, useSaveTheme } from "../hooks/theme"
+
+export function ThemeCustomizer() {
+  const [isDialogOpen, setIsDialogOpen] = React.useState(false)
+  const [currentTheme, setCurrentTheme] = React.useState<ThemeColor>(() => getCurrentTheme())
+  const saveTheme = useSaveTheme()
+
+  const handleThemeChange = (color: ThemeColor) => {
+    setCurrentTheme(color)
+    applyTheme(color)
+  }
+
+  const handleSave = async () => {
+    await saveTheme(currentTheme)
+    setIsDialogOpen(false)
+  }
+
+  return (
+    <Dialog open={isDialogOpen} onOpenChange={setIsDialogOpen}>
+      <Dialog.Trigger asChild>
+        <Button variant="secondary" size="small">
+          Customize Colors
+        </Button>
+      </Dialog.Trigger>
+      <Dialog.Content title="Theme Colors">
+        <div className="grid gap-4">
+          <div className="flex flex-col gap-2">
+            <label className="text-sm font-medium text-text-secondary">Color Theme</label>
+            <div className="flex gap-2 items-center">
+              {Object.entries(THEME_COLORS_MAP).map(([color, value]) => (
+                <Tooltip key={color}>
+                  <Tooltip.Trigger asChild>
+                    <button
+                      onClick={() => handleThemeChange(color as ThemeColor)}
+                      className="w-6 h-6 rounded-full cursor-pointer transition-transform hover:scale-110 focus:outline-none focus:ring-2 focus:ring-border-focus relative"
+                      style={{ backgroundColor: value }}
+                      aria-label={`Apply ${color} theme`}
+                    >
+                      {color === currentTheme && (
+                        <div className="absolute inset-0 rounded-full ring-2 ring-border-focus" />
+                      )}
+                    </button>
+                  </Tooltip.Trigger>
+                  <Tooltip.Content side="top">{color}</Tooltip.Content>
+                </Tooltip>
+              ))}
+            </div>
+          </div>
+          <div className="flex justify-end gap-3 mt-4">
+            <Button variant="secondary" size="small" onClick={() => setIsDialogOpen(false)}>
+              Cancel
+            </Button>
+            <Button variant="primary" size="small" onClick={handleSave}>
+              Save Changes
+            </Button>
+          </div>
+        </div>
+      </Dialog.Content>
+    </Dialog>
+  )
+}
diff --git a/src/hooks/theme.ts b/src/hooks/theme.ts
new file mode 100644
index 00000000..6271b2aa
--- /dev/null
+++ b/src/hooks/theme.ts
@@ -0,0 +1,139 @@
+import { useAtomValue, useSetAtom } from "jotai"
+import React from "react"
+import { globalStateMachineAtom, isRepoClonedAtom } from "../global-state"
+import { fs } from "../utils/fs"
+import { REPO_DIR } from "../utils/git"
+import path from "path"
+
+const THEME_COLORS = {
+  sand: "#dad9d6",
+  cyan: "#9ddde7",
+  yellow: "#f3d768",
+  amber: "#f3d673",
+  green: "#adddc0",
+  red: "#fdbdbe",
+  purple: "#e0c4f4",
+  orange: "#ffc182",
+} as const
+
+export type ThemeColor = keyof typeof THEME_COLORS
+export const THEME_COLORS_MAP = THEME_COLORS
+
+export function getCurrentTheme(): ThemeColor {
+  // Try to load saved theme from CSS variables
+  const style = getComputedStyle(document.documentElement)
+  const neutral6 = style.getPropertyValue("--neutral-6").trim()
+
+  // Find which theme matches the current neutral-6 value
+  const savedTheme = Object.entries(THEME_COLORS).find(([_, value]) => {
+    return neutral6 === value || neutral6 === `var(--${value}-6)`
+  })?.[0] as ThemeColor
+
+  return savedTheme || "sand"
+}
+
+export function applyTheme(color: ThemeColor) {
+  const cssVars = {} as Record<string, string>
+
+  // Update neutral scale variables
+  for (let i = 1; i <= 12; i++) {
+    const neutralVar = `--neutral-${i}`
+    const newColorVar = `--${color}-${i}`
+    cssVars[neutralVar] = `var(${newColorVar})`
+  }
+
+  // Update alpha variables
+  for (let i = 1; i <= 12; i++) {
+    const neutralVar = `--neutral-a${i}`
+    const newColorVar = `--${color}-a${i}`
+    cssVars[neutralVar] = `var(${newColorVar})`
+  }
+
+  // Apply colors immediately
+  Object.entries(cssVars).forEach(([variable, value]) => {
+    document.documentElement.style.setProperty(variable, value)
+  })
+
+  return cssVars
+}
+
+export function generateThemeCSS(cssVars: Record<string, string>) {
+  return `:root {
+${Object.entries(cssVars)
+  .map(([variable, value]) => `  ${variable}: ${value};`)
+  .join("\n")}
+}
+`
+}
+
+export function useLoadTheme() {
+  const isRepoCloned = useAtomValue(isRepoClonedAtom)
+
+  React.useEffect(() => {
+    if (!isRepoCloned) return
+
+    async function loadTheme() {
+      try {
+        // Try to read theme.css from the .lumen directory
+        const content = await fs.promises.readFile(`${REPO_DIR}/.lumen/theme.css`, "utf8")
+
+        // Create a style element
+        const style = document.createElement("style")
+        style.setAttribute("id", "custom-theme")
+        style.textContent = content.toString()
+
+        // Remove any existing custom theme
+        document.getElementById("custom-theme")?.remove()
+
+        // Add the new style element
+        document.head.appendChild(style)
+      } catch (error) {
+        // If theme.css doesn't exist, apply the default theme
+        console.debug("No custom theme found:", error)
+        applyTheme("sand")
+      }
+    }
+
+    loadTheme()
+  }, [isRepoCloned])
+}
+
+export function useSaveTheme() {
+  const send = useSetAtom(globalStateMachineAtom)
+
+  return React.useCallback(
+    async (color: ThemeColor) => {
+      const cssVars = applyTheme(color)
+      const cssContent = generateThemeCSS(cssVars)
+
+      // First ensure the .lumen directory exists
+      try {
+        const lumenDir = path.join(REPO_DIR, ".lumen")
+        try {
+          await fs.promises.stat(lumenDir)
+        } catch {
+          await fs.promises.mkdir(lumenDir)
+        }
+      } catch (error) {
+        console.debug("Error creating .lumen directory:", error)
+      }
+
+      // Save theme.css to the .lumen directory using the global state machine
+      send({
+        type: "WRITE_FILES",
+        markdownFiles: { ".lumen/theme.css": cssContent },
+        commitMessage: `Update theme colors to ${color}`,
+      })
+
+      // Also update the style element
+      const style = document.getElementById("custom-theme") || document.createElement("style")
+      style.setAttribute("id", "custom-theme")
+      style.textContent = cssContent
+
+      if (!style.parentElement) {
+        document.head.appendChild(style)
+      }
+    },
+    [send],
+  )
+}
diff --git a/src/routes/_appRoot.settings.tsx b/src/routes/_appRoot.settings.tsx
index 90b9e58d..dce60279 100644
--- a/src/routes/_appRoot.settings.tsx
+++ b/src/routes/_appRoot.settings.tsx
@@ -24,6 +24,7 @@ import {
 } from "../global-state"
 import { useEditorSettings } from "../hooks/editor-settings"
 import { cx } from "../utils/cx"
+import { ThemeCustomizer } from "../components/theme-customizer"
 
 export const Route = createFileRoute("/_appRoot/settings")({
   component: RouteComponent,
@@ -158,27 +159,32 @@ function ThemeSection() {
 
   return (
     <SettingsSection title="Theme">
-      <RadioGroup
-        aria-labelledby="theme-label"
-        value={theme}
-        defaultValue="default"
-        onValueChange={(value) => setTheme(value as "default" | "eink")}
-        className="flex flex-col gap-3 coarse:gap-4"
-        name="theme"
-      >
-        <div className="flex items-center gap-2">
-          <RadioGroup.Item id="theme-default" value="default" />
-          <label htmlFor="theme-default" className="select-none leading-4">
-            Default
-          </label>
-        </div>
-        <div className="flex items-center gap-2">
-          <RadioGroup.Item id="theme-eink" value="eink" />
-          <label htmlFor="theme-eink" className="select-none leading-4">
-            E-ink
-          </label>
-        </div>
-      </RadioGroup>
+      <div className="flex flex-col gap-4">
+        <RadioGroup
+          aria-labelledby="theme-label"
+          value={theme}
+          defaultValue="default"
+          onValueChange={(value) => setTheme(value as "default" | "eink")}
+          className="flex flex-col gap-3 coarse:gap-4"
+          name="theme"
+        >
+          <div className="flex items-center gap-2">
+            <RadioGroup.Item id="theme-default" value="default" />
+            <label htmlFor="theme-default" className="select-none leading-4">
+              Default
+            </label>
+          </div>
+          <div className="flex items-center gap-2">
+            <RadioGroup.Item id="theme-eink" value="eink" />
+            <label htmlFor="theme-eink" className="select-none leading-4">
+              E-ink
+            </label>
+          </div>
+        </RadioGroup>
+
+        <div className="h-px bg-border-secondary" />
+        <ThemeCustomizer />
+      </div>
     </SettingsSection>
   )
 }
diff --git a/src/routes/_appRoot.tsx b/src/routes/_appRoot.tsx
index 918d13ee..30082767 100644
--- a/src/routes/_appRoot.tsx
+++ b/src/routes/_appRoot.tsx
@@ -23,6 +23,7 @@ import {
 } from "../global-state"
 import { useSearchNotes } from "../hooks/search"
 import { useValueRef } from "../hooks/value-ref"
+import { useLoadTheme } from "../hooks/theme"
 
 export const Route = createFileRoute("/_appRoot")({
   component: RouteComponent,
@@ -49,6 +50,9 @@ function RouteComponent() {
   const { online } = useNetworkState()
   const rootRef = React.useRef<HTMLDivElement>(null)
 
+  // Load custom theme if available
+  useLoadTheme()
+
   // Sync when the app becomes visible again
   useEvent("visibilitychange", () => {
     if (document.visibilityState === "visible" && online) {
@@ -174,6 +178,7 @@ function RouteComponent() {
     ]
 
     sendVoiceConversation({ type: "ADD_TOOLS", tools })
+
     return () => {
       sendVoiceConversation({ type: "REMOVE_TOOLS", toolNames: tools.map((tool) => tool.name) })
     }