diff --git a/frontend/public/fonts/noto-sans-mongolian/SOURCE.md b/frontend/public/fonts/noto-sans-mongolian/SOURCE.md
index 844260e..9c38df4 100644
--- a/frontend/public/fonts/noto-sans-mongolian/SOURCE.md
+++ b/frontend/public/fonts/noto-sans-mongolian/SOURCE.md
@@ -7,5 +7,5 @@ Font copyright: Copyright 2018 Google Inc. All Rights Reserved.
 - License: SIL Open Font License 1.1; see the accompanying LICENSE.
 - Retrieved: 2026-11-08.
 
-Used only by the Unicode Mongolian sample in the development layout route.
+Used by the Mongolian UI at `/mn-Mong`.
 The font and license are served together from this directory.
diff --git a/frontend/src/App.tsx b/frontend/src/App.tsx
index dd76140..8ea37b4 100644
--- a/frontend/src/App.tsx
+++ b/frontend/src/App.tsx
@@ -26,7 +26,7 @@ import { isAuthorityDependentQuery, localesKeys, sessionKeys } from '@/lib/query
 import { isCountsPath } from '@/lib/routeLocales'
 import { switchPostFilterLocale } from '@/lib/posts'
 import { switchWikiLocale } from '@/lib/wiki'
-import { useLocale, useVerticalPreview } from '@/lib/useLocale'
+import { useLocale, useUILocale, useVerticalPreview } from '@/lib/useLocale'
 import { applyClientAnimationMode,
 	 applyClientAppearance,
 	 fetchUserThemeSlots,
@@ -46,7 +46,7 @@ import ServiceUnavailable from '@/pages/ServiceUnavailable'
 import type { ComponentType, Dispatch, FC, ReactNode, SetStateAction } from 'react'
 import type { RouteMatch } from 'react-router-dom'
 
-import type { AvailableLocale, LocaleCode } from '@/lib/locales'
+import type { AvailableLocale, LocaleCode, UILocaleCode } from '@/lib/locales'
 import type { PageRoute } from '@/lib/routeLocales'
 import type { User } from '@/types'
 
@@ -272,11 +272,16 @@ const RoutedApp = ({ locales }: { locales: AvailableLocale[] }) => {
   const robots = isCountsPath (location.pathname) ? 'noindex' : route?.route.handle?.robots
   const pagePath = unlocalisedPath (location.pathname)
   const countsPage = pagePath === '/counts' || pagePath.startsWith ('/counts/')
-  const switchLocale = async (targetLocale: LocaleCode): Promise<string> => {
+  const switchLocale = async (target: UILocaleCode): Promise<string> => {
+    const targetLocale = target === 'mn-Mong' ? 'ja' : target
+    if (targetLocale === locale)
+      return switchLocalePath (location, target)
     const resolve = route?.route.handle?.switchLocale
-    return (resolve != null && route != null)
-	? resolve ({ location, params: route.params, locale, targetLocale })
+    const destination =
+	(resolve != null && route != null)
+	? await resolve ({ location, params: route.params, locale, targetLocale })
 	: switchLocalePath (location, targetLocale)
+    return target === 'mn-Mong' ? `/mn-Mong${unlocalisedPath (destination)}` : destination
   }
   const [user, setUserState] = useState<User | null> (
       () => client.getQueryData<User> (sessionKeys.current) ?? null)
@@ -413,6 +418,7 @@ const RoutedApp = ({ locales }: { locales: AvailableLocale[] }) => {
 
 const LocaleRoute: FC = () => {
   const { locale } = useParams ()
+  const uiLocale = useUILocale ()
   const location = useLocation ()
   const verticalPreview = isVerticalPreviewPath (location.pathname)
   const { i18n } = useTranslation ()
@@ -433,10 +439,10 @@ const LocaleRoute: FC = () => {
 
   useLayoutEffect (() => {
     if (activeLocale != null)
-      document.documentElement.lang = activeLocale
-    if (activeLocale != null && i18n.language !== activeLocale)
-      void i18n.changeLanguage (activeLocale)
-  }, [activeLocale, i18n])
+      document.documentElement.lang = uiLocale
+    if (activeLocale != null && i18n.language !== uiLocale)
+      void i18n.changeLanguage (uiLocale)
+  }, [activeLocale, uiLocale, i18n])
 
   const redirect = legacyLocalePath (location, pathname => resolvePageRoute (pathname) != null)
   if (!(isLocaleCode (locale)) && !verticalPreview && redirect == null)
diff --git a/frontend/src/components/TopNav.tsx b/frontend/src/components/TopNav.tsx
index 4be2888..4720374 100644
--- a/frontend/src/components/TopNav.tsx
+++ b/frontend/src/components/TopNav.tsx
@@ -4,7 +4,7 @@ import { Globe } from 'lucide-react'
 import { Fragment, useEffect, useLayoutEffect, useRef, useState } from 'react'
 import { useLocation } from 'react-router-dom'
 
-import { useLocale, useLocaleNavigate, useVerticalPreview } from '@/lib/useLocale'
+import { useLocale, useLocaleNavigate, useUILocale, useVerticalPreview } from '@/lib/useLocale'
 import LocalisedText, { formatUIString } from '@/components/LocalisedText'
 import Separator from '@/components/MenuSeparator'
 import PrefetchLink from '@/components/PrefetchLink'
@@ -13,8 +13,10 @@ import TranslatedText from '@/components/TranslatedText'
 import { toast } from '@/components/ui/use-toast'
 import { WikiIdBus } from '@/lib/eventBus/WikiIdBus'
 import { isLocaleCode,
-	 localeFromPath,
+	 isUILocaleCode,
+	 MONGOLIAN_LOCALE,
 	 switchLocalePath,
+	 uiLocaleFromPath,
 	 unlocalisedPath } from '@/lib/locales'
 import { uiMessage, uiMessageLanguage } from '@/lib/messages'
 import { useUITranslation } from '@/lib/useUITranslation'
@@ -28,13 +30,13 @@ import { fetchWikiPage } from '@/lib/wiki'
 
 import type { FC, MouseEvent } from 'react'
 
-import type { AvailableLocale, LocaleCode } from '@/lib/locales'
+import type { AvailableLocale, UILocaleCode } from '@/lib/locales'
 import type { Material, Menu, MenuVisibleItem, Tag, User } from '@/types'
 
 type Props = {
     user: User | null
     locales: AvailableLocale[]
-    resolveLocaleSwitch?: (locale: LocaleCode) => Promise<string> }
+    resolveLocaleSwitch?: (locale: UILocaleCode) => Promise<string> }
 type NavDensity = 'auto' | 'comfortable' | 'compact'
 
 
@@ -47,7 +49,7 @@ export const menuOutline = (
 	pathName: string },
 ): Menu => {
   const pathName = unlocalisedPath (fullPathname)
-  const locale = localeFromPath (fullPathname) ?? 'ja'
+  const locale = uiLocaleFromPath (fullPathname)
 
   const message = (
       key: Parameters<typeof uiMessage>[1],
@@ -137,8 +139,11 @@ export const menuOutline = (
 const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
   const { message, label } = useUITranslation ('shared')
   const locale = useLocale ()
+  const uiLocale = useUILocale ()
   const verticalPreview = useVerticalPreview ()
-  const localeName = locales.find (entry => entry.code === locale)?.name
+  const uiLocales = [...locales.filter (entry => isLocaleCode (entry.code)),
+      ...(locales.some (entry => entry.code === 'ja') ? [MONGOLIAN_LOCALE] : [])]
+  const localeName = uiLocales.find (entry => entry.code === uiLocale)?.name
   const navigate = useLocaleNavigate ()
   const location = useLocation ()
   const currentLocation = useRef (location)
@@ -443,17 +448,18 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
 			rounded px-1 focus-within:ring-2">
 	<Globe aria-hidden="true" size={16}/>
 	<span className="top-nav-locale-name whitespace-nowrap text-sm">
-	  <LocalisedText language={locale}>{localeName}</LocalisedText>
+	  <LocalisedText language={uiLocale}>{localeName}</LocalisedText>
 	</span>
 	<select
-	    aria-label={formatUIString (localeName ?? '', locale)}
-	    value={locale}
+	    aria-label={formatUIString (localeName ?? '', uiLocale)}
+	    lang={uiLocale}
+	    value={uiLocale}
 	    disabled={switchingLocale}
 	    className="absolute inset-0 h-full w-full cursor-pointer opacity-0"
 	    onChange={async event => {
 	      const nextLocale = event.target.value
-	      if (isLocaleCode (nextLocale)
-		  && locales.some (entry => entry.code === nextLocale))
+	      if (isUILocaleCode (nextLocale)
+		  && uiLocales.some (entry => entry.code === nextLocale))
 	      {
 		const request = ++localeSwitchRequest.current
 		setSwitchingLocale (true)
@@ -478,8 +484,8 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
 		}
 	      }
 	    }}>
-	  {locales.map (entry => isLocaleCode (entry.code) && (
-	      <option key={entry.code} value={entry.code}>
+	  {uiLocales.map (entry => (
+	      <option key={entry.code} value={entry.code} lang={entry.code}>
 		{formatUIString (entry.name, entry.code)}
 	      </option>))}
 	</select>
@@ -489,7 +495,7 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
       <div ref={layoutRef} className="top-nav-layout w-full min-w-0 shrink-0"
 	  data-desktop={desktop ?? undefined} data-density={density}
 	  data-layout-ready={layoutReady}>
-	<nav ref={barRef} lang={uiMessageLanguage (locale, 'posts')}
+	<nav ref={barRef} lang={uiMessageLanguage (uiLocale, 'posts')}
 	    className="top-nav-root top-nav-bar flex justify-between items-center w-full">
 	  <div className="top-nav-primary flex shrink-0 items-center h-12">
 	    <PrefetchLink
@@ -560,18 +566,10 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
 	  <div className="top-nav-account ml-auto flex min-w-0 items-center gap-2">
 	    <TopNavUser user={user}/>
 	    {localeSelector}
-	    {verticalPreview && (
-		<span className="vertical-preview-sample" lang="mn-Mong">
-		  ᠮᠣᠩᠭᠣᠯ
-		</span>)}
 	  </div>
 
 	  <div className="top-nav-mobile-controls ml-auto flex shrink-0 items-center gap-2">
 	    {menuOpen && localeSelector}
-	    {verticalPreview && (
-		<span className="vertical-preview-sample" lang="mn-Mong">
-		  ᠮᠣᠩᠭᠣᠯ
-		</span>)}
 	    <button
 		type="button"
 		className="top-nav-mobile-toggle shrink-0 whitespace-nowrap
diff --git a/frontend/src/components/common/Form.tsx b/frontend/src/components/common/Form.tsx
index f97d669..877d3d4 100644
--- a/frontend/src/components/common/Form.tsx
+++ b/frontend/src/components/common/Form.tsx
@@ -8,7 +8,7 @@ type Props = {
 
 
 const Form: FC<Props> = ({ children, className }) => (
-    <div className={cn ('mx-auto max-w-xl space-y-4 p-4', className)}>
+    <div className={cn ('form-layout mx-auto max-w-xl space-y-4 p-4', className)}>
       {children}
     </div>)
 
diff --git a/frontend/src/components/layout/MainArea.tsx b/frontend/src/components/layout/MainArea.tsx
index 8ad772a..75329dc 100644
--- a/frontend/src/components/layout/MainArea.tsx
+++ b/frontend/src/components/layout/MainArea.tsx
@@ -17,7 +17,7 @@ type Props = {
 
 
 const MainArea: FC<Props> = (
-    { children, className, animateLayout = true, verticalContent = false },
+    { children, className, animateLayout = true, verticalContent = true },
 ) => {
   const behaviourSettings = useClientBehaviourSettings ()
   const verticalPreview = useVerticalPreview ()
diff --git a/frontend/src/entry-server.tsx b/frontend/src/entry-server.tsx
index 6205b50..e1f1fe9 100644
--- a/frontend/src/entry-server.tsx
+++ b/frontend/src/entry-server.tsx
@@ -10,7 +10,7 @@ import { AppFrame, appRoutes, resolvePageRoute } from '@/App'
 import { apiGet, isApiError } from '@/lib/api'
 import { createUII18n } from '@/lib/i18n'
 import { fetchLocales, isLocaleCode, isVerticalPreviewPath,
-	 legacyLocalePath } from '@/lib/locales'
+	 legacyLocalePath, uiLocaleFromPath } from '@/lib/locales'
 import { localesKeys, sessionKeys } from '@/lib/queryKeys'
 import { withRenderContext } from '@/lib/renderContext.server'
 
@@ -78,6 +78,7 @@ export const render = async (
   if (legacy != null && known != null)
     return { status: 308, location: legacy }
   const locale = isLocaleCode (segment) ? segment : 'ja'
+  const uiLocale = uiLocaleFromPath (pathname)
   const routePrefix = verticalPreview ? 'mn-Mong' : locale
   if (known?.route.handle?.redirectTo != null)
     return { status: 308,
@@ -117,7 +118,7 @@ export const render = async (
       if (prepare != null && known != null && status === 200)
 	status = await prepare ({ client, params: known.params, locale,
 	    searchParams: url.searchParams })
-      const instance = createUII18n (locale)
+      const instance = createUII18n (uiLocale)
       const handler = createStaticHandler (appRoutes)
       const context = await handler.query (new Request (url))
       if (context instanceof Response)
@@ -187,11 +188,11 @@ export const render = async (
 	      isAxiosError: true, response: {
 		status: isApiError (query.state.error) ? query.state.error.response?.status : 500 } } }
       })) }
-      const bootstrap = JSON.stringify ({ state, status, locale,
+      const bootstrap = JSON.stringify ({ state, status, locale: uiLocale,
 	  url: url.pathname + url.search })
 	  .replace (/</g, '\\u003c').replace (/\u2028/g, '\\u2028')
 	  .replace (/\u2029/g, '\\u2029')
-      return { status, html, head, locale, bootstrap,
+      return { status, html, head, locale: uiLocale, bootstrap,
 	  setCookies: requestContext.setCookies }
     }
     finally
diff --git a/frontend/src/index.css b/frontend/src/index.css
index 3676a42..f5402ee 100644
--- a/frontend/src/index.css
+++ b/frontend/src/index.css
@@ -626,17 +626,22 @@ body
   will-change: transform;
 }
 
-/* Loaded only by the development-only sample, with the OFL alongside the font. */
+/* Locally hosted Mongolian font; the OFL accompanies the font file. */
 @font-face
 {
-  font-family: 'BTRC Mongolian Preview';
+  font-family: 'BTRC Mongolian';
   src: url('/fonts/noto-sans-mongolian/NotoSansMongolian-Regular.ttf') format('truetype');
   font-weight: 400;
   font-style: normal;
   font-display: swap;
 }
 
-/* Development-only /mn-Mong layout. Unannotated pages retain horizontal text. */
+/* Mongolian flows down each line, then into the next column on the right. */
+:lang(mn-Mong)
+{
+  font-family: 'BTRC Mongolian', 'Mongolian Baiti', 'Noto Sans JP Variable', sans-serif;
+}
+
 [data-vertical-preview]
 {
   min-width: 0;
@@ -675,6 +680,56 @@ body
   overscroll-behavior-x: contain;
 }
 
+/* Specialised lists below retain their own grid and table layouts. */
+[data-vertical-preview] .main-area[data-vertical-content]:not(
+    .posts-main-area, .tags-main-area, .wiki-main-area)
+{
+  writing-mode: vertical-lr;
+  text-orientation: mixed;
+  text-align: start;
+  overflow-y: auto;
+}
+
+[data-vertical-preview] .main-area[data-vertical-content]:not(
+    .posts-main-area, .tags-main-area, .wiki-main-area) > :is(div, article, section)
+{
+  max-width: none;
+  max-inline-size: 100%;
+}
+
+[data-vertical-preview] .main-area[data-vertical-content] .prose
+{
+  max-width: none;
+  max-inline-size: 100%;
+}
+
+/* Input and data widgets keep their physical coordinates and nested scrolling. */
+[data-vertical-preview] .main-area[data-vertical-content] :is(
+    form, .form-layout, pre, .overflow-x-auto, .rc-md-editor, .not-prose)
+{
+  writing-mode: horizontal-tb;
+  text-orientation: mixed;
+  max-height: 100%;
+  overflow: auto;
+}
+
+[data-vertical-preview] .main-area[data-vertical-content] :is(form, .form-layout)
+{
+  width: min(36rem, calc(100vw - 2rem));
+}
+
+[data-vertical-preview] :where(.main-area[data-vertical-content]) :is(
+    button, input, select, textarea, code, time, table, img, video, iframe, canvas, svg)
+{
+  writing-mode: horizontal-tb;
+}
+
+[data-vertical-preview] .main-area[data-vertical-content] :is(img, video, iframe, canvas)
+{
+  max-height: 100%;
+  object-fit: contain;
+}
+
 [data-vertical-preview] .sidebar-panel
 {
   width: 100%;
@@ -741,16 +796,22 @@ body
   height: 1px;
 }
 
-[data-vertical-preview] .vertical-preview-sample
+[data-vertical-preview] .top-nav-locale-name:has(:lang(mn-Mong))
 {
+  display: inline;
   writing-mode: vertical-lr;
   text-orientation: mixed;
-  font-family: 'BTRC Mongolian Preview', 'Mongolian Baiti', sans-serif;
   font-size: 1.25rem;
   line-height: 1.5;
   flex-shrink: 0;
 }
 
+[data-vertical-preview] .top-nav-menu-link:has(.top-nav-locale-name)
+{
+  height: auto;
+  min-height: 2rem;
+}
+
 /* The post grid fills each column downwards before continuing to the right. */
 [data-vertical-preview] .posts-main-area > div
 {
diff --git a/frontend/src/lib/i18n.ts b/frontend/src/lib/i18n.ts
index 53d0a41..bd451b9 100644
--- a/frontend/src/lib/i18n.ts
+++ b/frontend/src/lib/i18n.ts
@@ -1,9 +1,11 @@
 import { createInstance } from 'i18next'
 import { initReactI18next } from 'react-i18next'
 
+import { MONGOLIAN_LOCALE, SUPPORTED_LOCALES } from '@/lib/locales'
+
 import type { i18n as I18n, TOptions } from 'i18next'
 
-import type { LocaleCode } from '@/lib/locales'
+import type { UILocaleCode } from '@/lib/locales'
 
 // Keep Japanese placeholders editable without reporting them as completed translations.
 const translatedResource = (resource: Record<string, unknown>): Record<string, unknown> => {
@@ -34,9 +36,14 @@ for (const [path, dictionary] of Object.entries (dictionaries))
   const [, , locale, filename] = path.split ('/')
   resources[locale] ??= { }
   resources[locale][filename.slice (0, -5)] =
-      locale === 'ain-Kana' ? translatedResource (dictionary) : dictionary
+      locale === 'ja' ? dictionary : translatedResource (dictionary)
 }
 const namespaces = Object.keys (resources.ja ?? { })
+// No Mongolian translations yet; preserve the existing fallback language metadata.
+resources[MONGOLIAN_LOCALE.code] ??= { }
+for (const namespace of namespaces)
+  resources[MONGOLIAN_LOCALE.code][namespace] ??=
+      translatedResource ({ _untranslated: ['*'] })
 
 
 export const createUII18n = (locale: string): I18n => {
@@ -44,7 +51,7 @@ export const createUII18n = (locale: string): I18n => {
   void instance.init ({
       lng: locale,
       fallbackLng: 'ja',
-      supportedLngs: ['ja', 'ain-Kana'],
+      supportedLngs: [...SUPPORTED_LOCALES, MONGOLIAN_LOCALE.code],
       load: 'currentOnly',
       initAsync: false,
       defaultNS: 'navigation',
@@ -122,7 +129,7 @@ export const languageUIMessage = (
 
 
 export const untranslatedKeys = (
-    locale: LocaleCode,
+    locale: UILocaleCode,
     namespace = 'navigation',
 ): string[] => {
   const collect = (resource: Record<string, unknown>, prefix = ''): string[] =>
diff --git a/frontend/src/lib/locales.ts b/frontend/src/lib/locales.ts
index 30b631c..afaca14 100644
--- a/frontend/src/lib/locales.ts
+++ b/frontend/src/lib/locales.ts
@@ -7,6 +7,10 @@ export const SUPPORTED_LOCALES = ['ja', 'ain-Kana'] as const
 
 export type LocaleCode = typeof SUPPORTED_LOCALES[number]
 
+// This UI locale uses Japanese content until the API supports Mongolian.
+export const MONGOLIAN_LOCALE = { code: 'mn-Mong', name: 'ᠮᠣᠩᠭᠣᠯ' } as const
+export type UILocaleCode = LocaleCode | typeof MONGOLIAN_LOCALE.code
+
 export type AvailableLocale = { code: string; name: string }
 
 
@@ -28,9 +32,17 @@ export const localeFromPath = (pathname: string): LocaleCode | null => {
 }
 
 
-// A development-only layout route; API and dictionary locales stay unchanged.
+// Frontend layout selection must not change the API's content locale.
 export const isVerticalPreviewPath = (pathname: string): boolean =>
-    import.meta.env.DEV && /^\/mn-Mong(?:[/?#]|$)/.test (pathname)
+    /^\/mn-Mong(?:[/?#]|$)/.test (pathname)
+
+
+export const isUILocaleCode = (value: unknown): value is UILocaleCode =>
+    value === MONGOLIAN_LOCALE.code || isLocaleCode (value)
+
+
+export const uiLocaleFromPath = (pathname: string): UILocaleCode =>
+    isVerticalPreviewPath (pathname) ? MONGOLIAN_LOCALE.code : localeFromPath (pathname) ?? 'ja'
 
 
 export const resolveViewingLocale = (
@@ -67,7 +79,7 @@ export const localiseTo = (to: To, locale: LocaleCode, viewingPath = ''): To =>
 
 export const switchLocalePath = (
     location: { pathname: string; search: string; hash: string },
-    locale: LocaleCode,
+    locale: UILocaleCode,
 ): string =>
     `/${ locale }${ unlocalisedPath (location.pathname) }${ location.search }${ location.hash }`
 
diff --git a/frontend/src/lib/messages.ts b/frontend/src/lib/messages.ts
index b8bd87a..d737d2d 100644
--- a/frontend/src/lib/messages.ts
+++ b/frontend/src/lib/messages.ts
@@ -1,19 +1,19 @@
 import { translateUIMessage } from '@/lib/i18n'
 
 import type navigation from '@/locales/ja/navigation.json'
-import type { LocaleCode } from '@/lib/locales'
+import type { UILocaleCode } from '@/lib/locales'
 
 export type UIMessageKey = keyof typeof navigation
 
 
 export const uiMessage = (
-    locale: LocaleCode,
+    locale: UILocaleCode,
     key: UIMessageKey,
     values: Record<string, string | number> = { },
 ): string => translateUIMessage (key, 'navigation', locale, values).text
 
 
-export const uiMessageLanguage = (locale: LocaleCode, key: UIMessageKey): 'ja' | 'ain' =>
+export const uiMessageLanguage = (locale: UILocaleCode, key: UIMessageKey): 'ja' | 'ain' =>
     translateUIMessage (key, 'navigation', locale).language === 'ain-Kana'
     ? 'ain'
     : 'ja'
diff --git a/frontend/src/lib/useLocale.ts b/frontend/src/lib/useLocale.ts
index 74dcaee..cdeb1f3 100644
--- a/frontend/src/lib/useLocale.ts
+++ b/frontend/src/lib/useLocale.ts
@@ -1,11 +1,12 @@
 import { useCallback } from 'react'
 import { useLocation, useNavigate, useParams } from 'react-router-dom'
 
-import { isVerticalPreviewPath, localiseTo, resolveViewingLocale } from '@/lib/locales'
+import { isVerticalPreviewPath, localiseTo,
+	 resolveViewingLocale, uiLocaleFromPath } from '@/lib/locales'
 
 import type { NavigateFunction, NavigateOptions, To } from 'react-router-dom'
 
-import type { LocaleCode } from '@/lib/locales'
+import type { LocaleCode, UILocaleCode } from '@/lib/locales'
 
 
 export const useLocale = (): LocaleCode => {
@@ -15,6 +16,10 @@ export const useLocale = (): LocaleCode => {
 }
 
 
+export const useUILocale = (): UILocaleCode =>
+    uiLocaleFromPath (useLocation ().pathname)
+
+
 export const useLocaleNavigate = (): NavigateFunction => {
   const navigate = useNavigate ()
   const locale = useLocale ()
diff --git a/frontend/src/lib/useUITranslation.ts b/frontend/src/lib/useUITranslation.ts
index 1281b0d..4fc259c 100644
--- a/frontend/src/lib/useUITranslation.ts
+++ b/frontend/src/lib/useUITranslation.ts
@@ -3,11 +3,11 @@ import { useTranslation } from 'react-i18next'
 
 import LocalisedText from '@/components/LocalisedText'
 import { translateUIMessage } from '@/lib/i18n'
-import { useLocale } from '@/lib/useLocale'
+import { useUILocale } from '@/lib/useLocale'
 
 
 export const useUITranslation = (namespace = 'common') => {
-  const locale = useLocale ()
+  const locale = useUILocale ()
   const { i18n } = useTranslation (namespace, { lng: locale })
 
   const message = useCallback ((key: string, values?: Record<string, string | number>) => {
diff --git a/frontend/src/main.tsx b/frontend/src/main.tsx
index e0a393c..faea692 100644
--- a/frontend/src/main.tsx
+++ b/frontend/src/main.tsx
@@ -6,7 +6,7 @@ import { I18nextProvider } from 'react-i18next'
 import '@/index.css'
 import App, { preloadPageRoute, resolvePageRoute } from '@/App'
 import { createUII18n } from '@/lib/i18n'
-import { currentViewingLocale } from '@/lib/locales'
+import { currentViewingLocale, uiLocaleFromPath } from '@/lib/locales'
 import { localesKeys } from '@/lib/queryKeys'
 import { applyClientAnimationMode, getClientAnimationMode } from '@/lib/settings'
 
@@ -22,7 +22,7 @@ const client = new QueryClient ({
 
 
 const mount = (serverRendered: boolean) => {
-  const instance = createUII18n (currentViewingLocale ())
+  const instance = createUII18n (uiLocaleFromPath (window.location.pathname))
   const app = (
       <HelmetProvider context={helmetContext}>
 	<QueryClientProvider client={client}>
diff --git a/frontend/src/pages/counts/CountsResourcePage.tsx b/frontend/src/pages/counts/CountsResourcePage.tsx
index b6be97f..5996306 100644
--- a/frontend/src/pages/counts/CountsResourcePage.tsx
+++ b/frontend/src/pages/counts/CountsResourcePage.tsx
@@ -359,7 +359,8 @@ const CountsResourceContent = (
 	      </ul>
 	    </nav>
 	  </SidebarComponent>
-	  <MainArea animateLayout={false} className="flex min-h-0 min-w-0 flex-col p-2">
+	  <MainArea animateLayout={false} verticalContent={false}
+	      className="flex min-h-0 min-w-0 flex-col p-2">
 	    <PageTitle className="mb-1 text-base" lang={title.language}>{title.text}</PageTitle>
 	    <div ref={controlsArea} className="shrink-0"
 		style={{ minHeight: definition == null ? controlsHeight : undefined }}>
diff --git a/frontend/src/pages/posts/PostDetailPage.tsx b/frontend/src/pages/posts/PostDetailPage.tsx
index 4513fb0..cdf5c8f 100644
--- a/frontend/src/pages/posts/PostDetailPage.tsx
+++ b/frontend/src/pages/posts/PostDetailPage.tsx
@@ -107,7 +107,7 @@ const PostDetailPage: FC<Props> = ({ user }) => {
 
 	{post && <TagDetailSidebar post={post} className="hidden md:block"/>}
 
-	<MainArea className="relative">
+	<MainArea className="relative" verticalContent={false}>
 	  {post
 	   ? (
 	      <>