diff --git a/services/web/frontend/js/features/ide-react/components/layout/main-layout.tsx b/services/web/frontend/js/features/ide-react/components/layout/main-layout.tsx
index a358f2c821..a14f82b6ee 100644
--- a/services/web/frontend/js/features/ide-react/components/layout/main-layout.tsx
+++ b/services/web/frontend/js/features/ide-react/components/layout/main-layout.tsx
@@ -1,6 +1,7 @@
 import { Panel, PanelGroup } from 'react-resizable-panels'
 import classNames from 'classnames'
 import { HorizontalResizeHandle } from '@/features/ide-react/components/resize/horizontal-resize-handle'
+import { VerticalResizeHandle } from '@/features/ide-react/components/resize/vertical-resize-handle'
 import PdfPreview from '@/features/pdf-preview/components/pdf-preview'
 import { RailLayout } from '../rail/rail'
 import { Toolbar } from '../toolbar/toolbar'
@@ -8,7 +9,7 @@ import { HorizontalToggler } from '@/features/ide-react/components/resize/horizo
 import { useTranslation } from 'react-i18next'
 import { usePdfPane } from '@/features/ide-react/hooks/use-pdf-pane'
 import { useLayoutContext } from '@/shared/context/layout-context'
-import { ElementType, useState } from 'react'
+import { ElementType, useEffect, useState } from 'react'
 import EditorPanel from '../editor/editor-panel'
 import { useRailContext } from '../../context/rail-context'
 import HistoryContainer from '@/features/ide-react/components/history-container'
@@ -25,6 +26,9 @@ const mainEditorLayoutModalsModules: Array<{
   path: string
 }> = importOverleafModules('mainEditorLayoutModals')
 
+// Bootstrap md breakpoint — below this we stack panels vertically on mobile
+const MOBILE_MQ = '(max-width: 767px)'
+
 export default function MainLayout() {
   const [resizing, setResizing] = useState(false)
   const { resizing: railResizing } = useRailContext()
@@ -38,8 +42,26 @@ export default function MainLayout() {
   } = usePdfPane()
   const { view, pdfLayout } = useLayoutContext()
 
+  const [isMobile, setIsMobile] = useState(
+    () => window.matchMedia(MOBILE_MQ).matches
+  )
+  useEffect(() => {
+    const mq = window.matchMedia(MOBILE_MQ)
+    const handler = (e: MediaQueryListEvent) => setIsMobile(e.matches)
+    mq.addEventListener('change', handler)
+    return () => mq.removeEventListener('change', handler)
+  }, [])
+
+  // verticalSplit is always vertical; sideBySide becomes vertical on mobile
+  const isVertical =
+    pdfLayout === 'verticalSplit' ||
+    (pdfLayout === 'sideBySide' && isMobile)
+
   const editorIsOpen =
-    view === 'editor' || view === 'file' || pdfLayout === 'sideBySide'
+    view === 'editor' ||
+    view === 'file' ||
+    pdfLayout === 'sideBySide' ||
+    pdfLayout === 'verticalSplit'
 
   const { t } = useTranslation()
 
@@ -58,8 +80,12 @@ export default function MainLayout() {
           <Panel id="ide-redesign-editor-and-pdf-panel" order={2}>
             <HistoryContainer />
             <PanelGroup
-              autoSaveId="ide-redesign-editor-and-pdf-panel-group"
-              direction="horizontal"
+              autoSaveId={
+                pdfLayout === 'verticalSplit'
+                  ? 'ide-redesign-editor-and-pdf-panel-group-vertical'
+                  : 'ide-redesign-editor-and-pdf-panel-group'
+              }
+              direction={isVertical ? 'vertical' : 'horizontal'}
               className={classNames({
                 hidden: view === 'history',
               })}
@@ -79,29 +105,38 @@ export default function MainLayout() {
                   <EditorPanel />
                 </div>
               </Panel>
-              <HorizontalResizeHandle
-                resizable={pdfLayout === 'sideBySide'}
-                onDragging={setResizing}
-                onDoubleClick={togglePdfPane}
-                hitAreaMargins={{ coarse: 0, fine: 0 }}
-                className={classNames({
-                  hidden: !editorIsOpen,
-                })}
-              >
-                <HorizontalToggler
-                  id="ide-redesign-pdf-panel"
-                  togglerType="east"
-                  isOpen={isPdfOpen}
-                  setIsOpen={setIsPdfOpen}
-                  tooltipWhenOpen={t('tooltip_hide_pdf')}
-                  tooltipWhenClosed={t('tooltip_show_pdf')}
+              {isVertical ? (
+                <VerticalResizeHandle
+                  onDragging={setResizing}
+                  className={classNames({
+                    hidden: !editorIsOpen,
+                  })}
                 />
-                {pdfLayout === 'sideBySide' && (
-                  <div className="synctex-controls">
-                    <DefaultSynctexControl />
-                  </div>
-                )}
-              </HorizontalResizeHandle>
+              ) : (
+                <HorizontalResizeHandle
+                  resizable={pdfLayout === 'sideBySide'}
+                  onDragging={setResizing}
+                  onDoubleClick={togglePdfPane}
+                  hitAreaMargins={{ coarse: 0, fine: 0 }}
+                  className={classNames({
+                    hidden: !editorIsOpen,
+                  })}
+                >
+                  <HorizontalToggler
+                    id="ide-redesign-pdf-panel"
+                    togglerType="east"
+                    isOpen={isPdfOpen}
+                    setIsOpen={setIsPdfOpen}
+                    tooltipWhenOpen={t('tooltip_hide_pdf')}
+                    tooltipWhenClosed={t('tooltip_show_pdf')}
+                  />
+                  {pdfLayout === 'sideBySide' && (
+                    <div className="synctex-controls">
+                      <DefaultSynctexControl />
+                    </div>
+                  )}
+                </HorizontalResizeHandle>
+              )}
               <Panel
                 collapsible
                 className={classNames('ide-redesign-pdf-container', {
diff --git a/services/web/frontend/js/features/ide-react/components/toolbar/change-layout-options.tsx b/services/web/frontend/js/features/ide-react/components/toolbar/change-layout-options.tsx
index ef1548ff32..97babf4697 100644
--- a/services/web/frontend/js/features/ide-react/components/toolbar/change-layout-options.tsx
+++ b/services/web/frontend/js/features/ide-react/components/toolbar/change-layout-options.tsx
@@ -15,7 +15,12 @@ import { isMac } from '@/shared/utils/os'
 import { Shortcut } from '@/shared/components/shortcut'
 import classNames from 'classnames'
 
-type LayoutOption = 'sideBySide' | 'editorOnly' | 'pdfOnly' | 'detachedPdf'
+type LayoutOption =
+  | 'sideBySide'
+  | 'verticalSplit'
+  | 'editorOnly'
+  | 'pdfOnly'
+  | 'detachedPdf'
 
 const getActiveLayoutOption = ({
   pdfLayout,
@@ -46,6 +51,10 @@ const getActiveLayoutOption = ({
     return 'sideBySide'
   }
 
+  if (pdfLayout === 'verticalSplit') {
+    return 'verticalSplit'
+  }
+
   return null
 }
 
@@ -92,12 +101,14 @@ const shortcuts: Record<LayoutOption, string[] | null> = isMac
       editorOnly: ['⌃', '⌘', '←'],
       pdfOnly: ['⌃', '⌘', '→'],
       sideBySide: ['⌃', '⌘', '↓'],
+      verticalSplit: null,
       detachedPdf: ['⌃', '⌘', '↑'],
     }
   : {
       editorOnly: null,
       pdfOnly: null,
       sideBySide: null,
+      verticalSplit: null,
       detachedPdf: null,
     }
 
@@ -136,6 +147,18 @@ export default function ChangeLayoutOptions() {
       >
         {t('split_view')}
       </LayoutDropdownItem>
+      <LayoutDropdownItem
+        onClick={() => handleChangeLayout('verticalSplit')}
+        active={activeLayoutOption === 'verticalSplit'}
+        leadingIcon="horizontal_split"
+        trailingIcon={
+          shortcuts.verticalSplit && (
+            <Shortcut keys={shortcuts.verticalSplit} />
+          )
+        }
+      >
+        {t('top_bottom_split_view')}
+      </LayoutDropdownItem>
       <LayoutDropdownItem
         onClick={() => handleChangeLayout('flat', 'editor')}
         active={activeLayoutOption === 'editorOnly'}
diff --git a/services/web/frontend/js/features/ide-react/hooks/use-pdf-pane.ts b/services/web/frontend/js/features/ide-react/hooks/use-pdf-pane.ts
index 0a232edcbe..e21026ae70 100644
--- a/services/web/frontend/js/features/ide-react/hooks/use-pdf-pane.ts
+++ b/services/web/frontend/js/features/ide-react/hooks/use-pdf-pane.ts
@@ -8,7 +8,8 @@ export const usePdfPane = () => {
     useLayoutContext()
 
   const pdfPanelRef = useRef<ImperativePanelHandle>(null)
-  const pdfIsOpen = pdfLayout === 'sideBySide' || view === 'pdf'
+  const pdfIsOpen =
+    pdfLayout === 'sideBySide' || pdfLayout === 'verticalSplit' || view === 'pdf'
 
   useCollapsiblePanel(pdfIsOpen, pdfPanelRef)
 
@@ -46,7 +47,7 @@ export const usePdfPane = () => {
 
   // triggered when the PDF pane becomes closed (either by dragging or toggling)
   const handlePdfPaneCollapse = useCallback(() => {
-    if (pdfLayout === 'sideBySide') {
+    if (pdfLayout === 'sideBySide' || pdfLayout === 'verticalSplit') {
       changeLayout('flat', 'editor')
     }
   }, [changeLayout, pdfLayout])
diff --git a/services/web/frontend/js/features/pdf-preview/components/switch-to-editor-button.tsx b/services/web/frontend/js/features/pdf-preview/components/switch-to-editor-button.tsx
index 7eaa4bfb3d..503870a198 100644
--- a/services/web/frontend/js/features/pdf-preview/components/switch-to-editor-button.tsx
+++ b/services/web/frontend/js/features/pdf-preview/components/switch-to-editor-button.tsx
@@ -12,7 +12,7 @@ function SwitchToEditorButton() {
     return null
   }
 
-  if (pdfLayout === 'sideBySide') {
+  if (pdfLayout === 'sideBySide' || pdfLayout === 'verticalSplit') {
     return null
   }
 
diff --git a/services/web/frontend/js/features/source-editor/components/switch-to-pdf-button.tsx b/services/web/frontend/js/features/source-editor/components/switch-to-pdf-button.tsx
index 1cd2a4140a..2bd8cefab1 100644
--- a/services/web/frontend/js/features/source-editor/components/switch-to-pdf-button.tsx
+++ b/services/web/frontend/js/features/source-editor/components/switch-to-pdf-button.tsx
@@ -12,7 +12,7 @@ function SwitchToPDFButton() {
     return null
   }
 
-  if (pdfLayout === 'sideBySide') {
+  if (pdfLayout === 'sideBySide' || pdfLayout === 'verticalSplit') {
     return null
   }
 
diff --git a/services/web/frontend/js/shared/context/layout-context.tsx b/services/web/frontend/js/shared/context/layout-context.tsx
index 821834a9ac..32eae290ab 100644
--- a/services/web/frontend/js/shared/context/layout-context.tsx
+++ b/services/web/frontend/js/shared/context/layout-context.tsx
@@ -25,7 +25,7 @@ import usePersistedState from '@/shared/hooks/use-persisted-state'
 import { repositionAllTooltips } from '@/features/source-editor/extensions/tooltips-reposition'
 import { useEditorAnalytics } from '@/shared/hooks/use-editor-analytics'
 
-export type IdeLayout = 'sideBySide' | 'flat'
+export type IdeLayout = 'sideBySide' | 'flat' | 'verticalSplit'
 export type IdeView = 'editor' | 'file' | 'pdf' | 'history'
 
 export type LayoutContextOwnStates = {
@@ -77,7 +77,11 @@ export const LayoutContext = createContext<LayoutContextValue | undefined>(
 function setLayoutInLocalStorage(pdfLayout: IdeLayout) {
   localStorage.setItem(
     'pdf.layout',
-    pdfLayout === 'sideBySide' ? 'split' : 'flat'
+    pdfLayout === 'sideBySide'
+      ? 'split'
+      : pdfLayout === 'verticalSplit'
+        ? 'vertical'
+        : 'flat'
   )
 }
 
@@ -199,7 +203,10 @@ export const LayoutProvider: FC<React.PropsWithChildren> = ({ children }) => {
 
   const changeLayout = useCallback(
     (newLayout: IdeLayout, newView: IdeView = 'editor') => {
-      const targetView = newLayout === 'sideBySide' ? 'editor' : newView
+      const targetView =
+        newLayout === 'sideBySide' || newLayout === 'verticalSplit'
+          ? 'editor'
+          : newView
       setPdfLayout(newLayout)
       if (targetView === 'editor') {
         restoreView()
@@ -230,7 +237,10 @@ export const LayoutProvider: FC<React.PropsWithChildren> = ({ children }) => {
   } = useDetachLayout()
 
   const pdfPreviewOpen =
-    pdfLayout === 'sideBySide' || view === 'pdf' || detachRole === 'detacher'
+    pdfLayout === 'sideBySide' ||
+    pdfLayout === 'verticalSplit' ||
+    view === 'pdf' ||
+    detachRole === 'detacher'
 
   useEffect(() => {
     if (debugPdfDetach) {
diff --git a/services/web/locales/en.json b/services/web/locales/en.json
index 12246a6fca..bae3a39fc7 100644
--- a/services/web/locales/en.json
+++ b/services/web/locales/en.json
@@ -2485,6 +2485,7 @@
   "spellcheck_language": "Spellcheck language",
   "spelling_and_language": "Spelling and language",
   "split_view": "Split view",
+  "top_bottom_split_view": "Top / bottom split",
   "sso": "SSO",
   "sso_account_already_linked": "Account already linked to another __appName__ user",
   "sso_active": "SSO active",
diff --git a/services/web/locales/fr.json b/services/web/locales/fr.json
index a37a99174b..8e7c5908a1 100644
--- a/services/web/locales/fr.json
+++ b/services/web/locales/fr.json
@@ -2490,6 +2490,7 @@
   "spellcheck_language": "Langue de vérification orthographique",
   "spelling_and_language": "Orthographe et langue",
   "split_view": "Vue fractionnée",
+  "top_bottom_split_view": "Vue haute / basse",
   "sso": "SSO",
   "sso_account_already_linked": "Compte déjà lié à un·e autre utilisateur·rice __appName__",
   "sso_active": "SSO actif",