diff --git a/components/BuilderClientPage.tsx b/components/BuilderClientPage.tsx
index c9eec70..192f586 100644
--- a/components/BuilderClientPage.tsx
+++ b/components/BuilderClientPage.tsx
@@ -223,7 +223,13 @@ export default function BuilderClientPage() {
     if (manifestShortName && manifestShortName.trim().length > 0) manifestOverrideBase.short_name = manifestShortName.trim()
     if (manifestStartUrl && manifestStartUrl.trim().length > 0) manifestOverrideBase.start_url = manifestStartUrl.trim()
     if (manifestDisplay && manifestDisplay.trim().length > 0) manifestOverrideBase.display = manifestDisplay.trim()
-    if (manifestThemeColor && manifestThemeColor.trim().length > 0) manifestOverrideBase.theme_color = manifestThemeColor.trim()
+    if (manifestThemeColor && manifestThemeColor.trim().length > 0) {
+      const v = manifestThemeColor.trim()
+      const hexOk = /^#([0-9a-fA-F]{3}){1,2}$/.test(v)
+      if (hexOk) {
+        manifestOverrideBase.theme_color = v
+      }
+    }
     const manifestOverride = Object.keys(manifestOverrideBase).length > 0 ? (manifestOverrideBase as { name?: string; short_name?: string; start_url?: string; display?: string; theme_color?: string }) : undefined
     const robotsTextOverride = (() => {
       const lines = (robotsDisallow || '').split(/\n+/).map((s) => s.trim()).filter((s) => s.length > 0)
@@ -334,14 +340,18 @@ export default function BuilderClientPage() {
               </label>
               <label className="block" htmlFor="ins-manifest-display">
                 <span className="sr-only">Manifest Display</span>
-                <input
+                <select
                   id="ins-manifest-display"
                   aria-label="Manifest Display"
                   className="border rounded px-3 py-2 w-full"
                   value={manifestDisplay}
                   onChange={(e) => setManifestDisplay(e.target.value)}
-                  placeholder="standalone"
-                />
+                >
+                  <option value="">(default)</option>
+                  <option value="standalone">standalone</option>
+                  <option value="minimal-ui">minimal-ui</option>
+                  <option value="browser">browser</option>
+                </select>
               </label>
               <label className="block" htmlFor="ins-manifest-theme-color">
                 <span className="sr-only">Manifest Theme Color</span>
diff --git a/components/ExportOptions.polish.ui.test.tsx b/components/ExportOptions.polish.ui.test.tsx
new file mode 100644
index 0000000..32e2874
--- /dev/null
+++ b/components/ExportOptions.polish.ui.test.tsx
@@ -0,0 +1,64 @@
+import { describe, it, expect, vi } from 'vitest'
+import { render, screen, fireEvent } from '@testing-library/react'
+import BuilderClientPage from '@/components/BuilderClientPage'
+
+vi.mock('next-intl', () => {
+  return {
+    useTranslations: () => (key: string) => key,
+  }
+})
+
+const buildZipSpy = vi.fn(async (_arg: {
+  html: string
+  css: string
+  js: string
+  assets: Record<string, Uint8Array>
+  extras?: Record<string, Uint8Array>
+}) => new Uint8Array([80, 75]))
+
+vi.mock('@/lib/exporter/zip', () => {
+  return {
+    buildZip: (arg: {
+      html: string
+      css: string
+      js: string
+      assets: Record<string, Uint8Array>
+      extras?: Record<string, Uint8Array>
+    }) => buildZipSpy(arg),
+  }
+})
+
+describe('Export Options UI polish', () => {
+  it('uses a dropdown for Manifest Display and passes selected value', async () => {
+    render(<BuilderClientPage />)
+
+    // choose display = minimal-ui
+    const displaySelect = await screen.findByLabelText('Manifest Display')
+    fireEvent.change(displaySelect, { target: { value: 'minimal-ui' } })
+
+    const exportBtn = await screen.findByRole('button', { name: 'builder.action.export' })
+    fireEvent.click(exportBtn)
+
+    const first = buildZipSpy.mock.calls[0]
+    const extras: Record<string, Uint8Array> = (first![0] as { extras: Record<string, Uint8Array> }).extras
+    const td = new TextDecoder()
+    const manifest = JSON.parse(td.decode(extras['site.webmanifest']))
+    expect(manifest.display).toBe('minimal-ui')
+  })
+
+  it('ignores invalid theme_color override and keeps default theme when not a hex', async () => {
+    render(<BuilderClientPage />)
+
+    const colorInput = await screen.findByLabelText('Manifest Theme Color')
+    fireEvent.change(colorInput, { target: { value: 'blue' } }) // invalid hex
+
+    const exportBtn = await screen.findByRole('button', { name: 'builder.action.export' })
+    fireEvent.click(exportBtn)
+
+    const first = buildZipSpy.mock.calls[0]
+    const extras: Record<string, Uint8Array> = (first![0] as { extras: Record<string, Uint8Array> }).extras
+    const td = new TextDecoder()
+    const manifest = JSON.parse(td.decode(extras['site.webmanifest']))
+    expect(manifest.theme_color).toBe('#0ea5e9') // default from page.theme.primaryColor
+  })
+})