diff --git a/src/apps/chat/components/ChatMessageList.tsx b/src/apps/chat/components/ChatMessageList.tsx
index ec287a394..28fc0557c 100644
--- a/src/apps/chat/components/ChatMessageList.tsx
+++ b/src/apps/chat/components/ChatMessageList.tsx
@@ -17,7 +17,6 @@ import { createDMessageFromFragments, createDMessageTextContent, DMessage, DMess
 import { createTextContentFragment, DMessageFragment, DMessageFragmentId } from '~/common/stores/chat/chat.fragments';
 import { openFileForAttaching } from '~/common/components/ButtonAttachFiles';
 import { optimaOpenPreferences } from '~/common/layout/optima/useOptima';
-import { useBrowserTranslationWarning } from '~/common/components/useIsBrowserTranslating';
 import { useCapabilityElevenLabs } from '~/common/components/useCapabilities';
 import { useChatOverlayStore } from '~/common/chat-overlay/store-perchat_vanilla';
 import { useChatStore } from '~/common/stores/chat/store-chats';
@@ -65,7 +64,6 @@ export function ChatMessageList(props: {
   const { notifyBooting } = useScrollToBottom();
   const danger_experimentalHtmlWebUi = useChatAutoSuggestHTMLUI();
   const [showSystemMessages] = useChatShowSystemMessages();
-  const optionalTranslationWarning = useBrowserTranslationWarning();
   const { conversationMessages, historyTokenCount } = useChatStore(useShallow(({ conversations }) => {
     const conversation = conversations.find(conversation => conversation.id === props.conversationId);
     return {
@@ -326,8 +324,6 @@ export function ChatMessageList(props: {
   return (
     <List role='chat-messages-list' sx={listSx}>
 
-      {optionalTranslationWarning}
-
       {props.isMessageSelectionMode && (
         <MessagesSelectionHeader
           hasSelected={selectedMessages.size > 0}
diff --git a/src/common/components/useIsBrowserInPWADesktop.tsx b/src/common/components/useIsBrowserInPWADesktop.tsx
new file mode 100644
index 000000000..7e5217b8f
--- /dev/null
+++ b/src/common/components/useIsBrowserInPWADesktop.tsx
@@ -0,0 +1,66 @@
+import * as React from 'react';
+
+import { Alert, IconButton } from '@mui/joy';
+import CloseRoundedIcon from '@mui/icons-material/CloseRounded';
+import WarningRoundedIcon from '@mui/icons-material/WarningRounded';
+
+import { Is, isBrowser, isPwa } from '~/common/util/pwaUtils';
+import { useUICounter } from '~/common/stores/store-ui';
+
+
+/**
+ * Detects if a mobile PWA is running in Desktop Mode (which causes layout issues).
+ * This happens when Chrome's "Request Desktop Site" is enabled on mobile devices.
+ *
+ * Shows a dismissible warning when:
+ * - App is running as a PWA (standalone mode)
+ * - Device OS is mobile (iOS or Android)
+ * - Viewport width is >= 900px (indicating desktop mode override)
+ */
+export function usePWADesktopModeWarning() {
+
+  // state
+  const [hideWarning, setHideWarning] = React.useState(false);
+
+  // external state
+  const { novel: lessThanFive, touch } = useUICounter('acknowledge-pwa-desktop-mode-warning', 5);
+
+  // detect PWA in desktop mode
+  const isInDesktopMode = React.useMemo(() => {
+    if (!isBrowser) return false;
+
+    // if PWA
+    const isInPwaMode = isPwa();
+    if (!isInPwaMode) return false;
+
+    // if OS is mobile
+    const isMobileOS = Is.OS.iOS || Is.OS.Android;
+    if (!isMobileOS) return false;
+
+    // Check if viewport width suggests desktop mode (>= 900px)
+    // This matches the mobile breakpoint used in useMatchMedia.ts
+    return window.matchMedia('(min-width: 900px)').matches;
+  }, []);
+
+  const showWarning = isInDesktopMode && !hideWarning && lessThanFive;
+
+  return React.useMemo(() => showWarning ? (
+    <Alert
+      size='lg'
+      variant='soft'
+      color='warning'
+      startDecorator={<WarningRoundedIcon />}
+      endDecorator={
+        <IconButton color='warning'>
+          <CloseRoundedIcon onClick={() => {
+            setHideWarning(true);
+            touch();
+          }} />
+        </IconButton>
+      }
+    >
+      This Browser is running in Desktop Mode, which may cause layout issues.<br />
+      To fix: Close this app, open Chrome, visit this site, disable &quot;Desktop site&quot; in the menu, then reopen the app.
+    </Alert>
+  ) : null, [showWarning, touch]);
+}
diff --git a/src/common/layout/optima/OptimaLayout.tsx b/src/common/layout/optima/OptimaLayout.tsx
index d4a0d98ba..e4b3a8cda 100644
--- a/src/common/layout/optima/OptimaLayout.tsx
+++ b/src/common/layout/optima/OptimaLayout.tsx
@@ -5,8 +5,10 @@ import { PanelGroup } from 'react-resizable-panels';
 import { GlobalDragOverlay } from '~/common/components/dnd-dt/GlobalDragOverlay';
 import { Is } from '~/common/util/pwaUtils';
 import { checkVisibleNav, navItems } from '~/common/app.nav';
+import { useBrowserTranslationWarning } from '~/common/components/useIsBrowserTranslating';
 import { useGlobalShortcuts } from '~/common/components/shortcuts/useGlobalShortcuts';
 import { useIsMobile } from '~/common/components/useMatchMedia';
+import { usePWADesktopModeWarning } from '~/common/components/useIsBrowserInPWADesktop';
 import { useUIPreferencesStore } from '~/common/stores/store-ui';
 
 import { ScratchClip } from './scratchclip/ScratchClip';
@@ -61,6 +63,10 @@ export function OptimaLayout(props: { suspendAutoModelsSetup?: boolean, children
   // derived state
   const currentApp = navItems.apps.find(item => item.route === route);
 
+  // global warnings
+  const translationWarning = useBrowserTranslationWarning();
+  const pwaDesktopModeWarning = usePWADesktopModeWarning();
+
   // global shortcuts for Optima
   useGlobalShortcuts('OptimaApp', React.useMemo(() => [
     // Preferences & Model dialogs
@@ -78,6 +84,10 @@ export function OptimaLayout(props: { suspendAutoModelsSetup?: boolean, children
 
   return <>
 
+    {/* Global Warnings */}
+    {translationWarning}
+    {pwaDesktopModeWarning}
+
     <PanelGroup direction='horizontal' id='root-layout' style={isMobile ? undoPanelGroupSx : undefined}>
 
 
diff --git a/src/common/stores/store-ui.ts b/src/common/stores/store-ui.ts
index 7da40375c..f9f517b77 100644
--- a/src/common/stores/store-ui.ts
+++ b/src/common/stores/store-ui.ts
@@ -245,6 +245,7 @@ export function uiSetPanelGroupCollapsed(key: string, collapsed: boolean): void
 //  'export-share'                    // used the export function
 //  'share-chat-link'                 // not shared a Chat Link yet
 type KnownKeys =
+  | 'acknowledge-pwa-desktop-mode-warning' // displayed if mobile PWA is in desktop mode (layout issues)
   | 'acknowledge-translation-warning' // displayed if Chrome is translating the page (may crash)
   | 'beam-wizard'                     // first Beam
   | 'call-wizard'                     // first Call