diff --git a/frontend/src/components/TopNav.tsx b/frontend/src/components/TopNav.tsx
index 4720374..7859858 100644
--- a/frontend/src/components/TopNav.tsx
+++ b/frontend/src/components/TopNav.tsx
@@ -12,9 +12,7 @@ import TopNavUser from '@/components/TopNavUser'
 import TranslatedText from '@/components/TranslatedText'
 import { toast } from '@/components/ui/use-toast'
 import { WikiIdBus } from '@/lib/eventBus/WikiIdBus'
-import { isLocaleCode,
-	 isUILocaleCode,
-	 MONGOLIAN_LOCALE,
+import { isUILocaleCode,
 	 switchLocalePath,
 	 uiLocaleFromPath,
 	 unlocalisedPath } from '@/lib/locales'
@@ -141,8 +139,7 @@ const TopNav: FC<Props> = ({ user, locales, resolveLocaleSwitch }) => {
   const locale = useLocale ()
   const uiLocale = useUILocale ()
   const verticalPreview = useVerticalPreview ()
-  const uiLocales = [...locales.filter (entry => isLocaleCode (entry.code)),
-      ...(locales.some (entry => entry.code === 'ja') ? [MONGOLIAN_LOCALE] : [])]
+  const uiLocales = locales.filter (entry => isUILocaleCode (entry.code))
   const localeName = uiLocales.find (entry => entry.code === uiLocale)?.name
   const navigate = useLocaleNavigate ()
   const location = useLocation ()
diff --git a/frontend/src/index.css b/frontend/src/index.css
index f5402ee..b6dac0c 100644
--- a/frontend/src/index.css
+++ b/frontend/src/index.css
@@ -756,14 +756,32 @@ body
 
 [data-vertical-preview] .sidebar > form
 {
-  width: 16rem;
+  display: flex;
+  align-items: flex-start;
+  gap: .5rem;
+  width: auto;
   height: 100%;
-  overflow-y: auto;
+}
+
+[data-vertical-preview] .sidebar > form > input[type='text']
+{
+  writing-mode: vertical-lr;
+  text-orientation: mixed;
+  width: auto;
+  height: 100%;
+  min-height: 0;
+  padding: .75rem .5rem;
 }
 
 [data-vertical-preview] .sidebar > form > ul
 {
   position: relative;
+  left: auto;
+  right: auto;
+  flex-shrink: 0;
+  width: min(16rem, 75vw);
+  max-height: 100%;
+  overflow-y: auto;
 }
 
 [data-vertical-preview] .sidebar > div