diff --git a/src/app/components/AnimatedOutlet.tsx b/src/app/components/AnimatedOutlet.tsx
index fc9af0a..9a8eb58 100644
--- a/src/app/components/AnimatedOutlet.tsx
+++ b/src/app/components/AnimatedOutlet.tsx
@@ -47,7 +47,16 @@ export function AnimatedOutlet() {
     pendingRoomId !== selectedRoomId;
 
   return (
-    <div style={{ flex: 1, minWidth: 0, minHeight: 0, position: 'relative', display: 'flex' }}>
+    <div
+      style={{
+        flex: 1,
+        minWidth: 0,
+        minHeight: 0,
+        position: 'relative',
+        display: 'flex',
+        flexDirection: 'column',
+      }}
+    >
       {showOverlay && <PendingRoomShell roomId={pendingRoomId} />}
       {/*
         Do NOT key this by pathname — room switches share CachedRooms keep-alive.
diff --git a/src/app/components/RenderMessageContent.tsx b/src/app/components/RenderMessageContent.tsx
index 9891f98..5e8124f 100644
--- a/src/app/components/RenderMessageContent.tsx
+++ b/src/app/components/RenderMessageContent.tsx
@@ -46,6 +46,7 @@ type RenderMessageContentProps = {
   urlPreview?: boolean;
   highlightRegex?: RegExp;
   htmlReactParserOptions: HTMLReactParserOptions;
+  jumboHtmlReactParserOptions?: HTMLReactParserOptions;
   linkifyOpts: Opts;
   outlineAttachment?: boolean;
   disabledEmbedPatterns?: string[];
@@ -60,6 +61,7 @@ export function RenderMessageContent({
   urlPreview,
   highlightRegex,
   htmlReactParserOptions,
+  jumboHtmlReactParserOptions,
   linkifyOpts,
   outlineAttachment,
   disabledEmbedPatterns,
@@ -113,6 +115,7 @@ export function RenderMessageContent({
               {...props}
               highlightRegex={highlightRegex}
               htmlReactParserOptions={htmlReactParserOptions}
+              jumboHtmlReactParserOptions={jumboHtmlReactParserOptions}
               linkifyOpts={linkifyOpts}
             />
           )}
@@ -187,6 +190,7 @@ export function RenderMessageContent({
             {...props}
             highlightRegex={highlightRegex}
             htmlReactParserOptions={htmlReactParserOptions}
+            jumboHtmlReactParserOptions={jumboHtmlReactParserOptions}
             linkifyOpts={linkifyOpts}
           />
         )}
@@ -206,6 +210,7 @@ export function RenderMessageContent({
             {...props}
             highlightRegex={highlightRegex}
             htmlReactParserOptions={htmlReactParserOptions}
+            jumboHtmlReactParserOptions={jumboHtmlReactParserOptions}
             linkifyOpts={linkifyOpts}
           />
         )}
@@ -224,6 +229,7 @@ export function RenderMessageContent({
             {...props}
             highlightRegex={highlightRegex}
             htmlReactParserOptions={htmlReactParserOptions}
+            jumboHtmlReactParserOptions={jumboHtmlReactParserOptions}
             linkifyOpts={linkifyOpts}
           />
         )}
diff --git a/src/app/components/message/RenderBody.tsx b/src/app/components/message/RenderBody.tsx
index 501ca30..ef57315 100644
--- a/src/app/components/message/RenderBody.tsx
+++ b/src/app/components/message/RenderBody.tsx
@@ -5,6 +5,9 @@ import { Opts } from 'linkifyjs';
 import { MessageEmptyContent } from './content';
 import { sanitizeCustomHtml } from '../../utils/sanitize';
 import { highlightText, scaleSystemEmoji } from '../../plugins/react-custom-html-parser';
+import { isMxEmoticonOnlyHtml } from '../../utils/regex';
+// Ensure jumbo emoji global styles are always in the bundle.
+import './layout/layout.css';
 
 type RenderBodyProps = {
   body: string;
@@ -13,6 +16,7 @@ type RenderBodyProps = {
 
   highlightRegex?: RegExp;
   htmlReactParserOptions: HTMLReactParserOptions;
+  jumboHtmlReactParserOptions?: HTMLReactParserOptions;
   linkifyOpts: Opts;
 };
 export function RenderBody({
@@ -21,13 +25,22 @@ export function RenderBody({
   jumbo = false,
   highlightRegex,
   htmlReactParserOptions,
+  jumboHtmlReactParserOptions,
   linkifyOpts,
 }: RenderBodyProps) {
-  if (body === '') <MessageEmptyContent />;
-  if (customBody) {
-    if (customBody === '') <MessageEmptyContent />;
-    return parse(sanitizeCustomHtml(customBody), htmlReactParserOptions);
+  const hasCustomBody = typeof customBody === 'string' && customBody.length > 0;
+  // Unicode jumbo should use the plain path so scaleSystemEmoji gets the jumbo flag.
+  // HTML path is only needed for custom mx-emoticon images.
+  const useCustomHtml = hasCustomBody && (!jumbo || isMxEmoticonOnlyHtml(customBody));
+
+  if (useCustomHtml) {
+    const options =
+      jumbo && jumboHtmlReactParserOptions ? jumboHtmlReactParserOptions : htmlReactParserOptions;
+    return parse(sanitizeCustomHtml(customBody), options);
   }
+
+  if (body === '') return <MessageEmptyContent />;
+
   return (
     <Linkify options={linkifyOpts}>
       {highlightRegex
diff --git a/src/app/features/room/CachedRooms.tsx b/src/app/features/room/CachedRooms.tsx
index b310b53..a0ab477 100644
--- a/src/app/features/room/CachedRooms.tsx
+++ b/src/app/features/room/CachedRooms.tsx
@@ -20,7 +20,9 @@ const activeSlotStyle: React.CSSProperties = {
   flex: 1,
   minWidth: 0,
   minHeight: 0,
+  width: '100%',
   display: 'flex',
+  flexDirection: 'column',
   position: 'relative',
   zIndex: 1,
 };
@@ -29,11 +31,12 @@ const inactiveSlotStyle: React.CSSProperties = {
   position: 'absolute',
   inset: 0,
   display: 'flex',
-  // Prefer opacity over visibility:hidden — the latter can reset overflow scrollTop.
-  opacity: 0,
+  flexDirection: 'column',
+  // Scroll is saved/restored manually — hide without opacity so we don't stack
+  // compositor layers over the active room (looked like an all-black chat pane).
+  visibility: 'hidden',
   pointerEvents: 'none',
-  zIndex: 0,
-  // Keep in layout for scroll metrics; inert + aria-hidden handle a11y.
+  zIndex: -1,
 };
 
 type CachedRoomSlotProps = {
@@ -175,8 +178,10 @@ export function CachedRooms() {
         flex: 1,
         minWidth: 0,
         minHeight: 0,
+        width: '100%',
         position: 'relative',
         display: 'flex',
+        flexDirection: 'column',
       }}
     >
       {ids.map((roomId) => {
diff --git a/src/app/features/room/Room.tsx b/src/app/features/room/Room.tsx
index bf383e2..b77be59 100644
--- a/src/app/features/room/Room.tsx
+++ b/src/app/features/room/Room.tsx
@@ -53,7 +53,7 @@ export const RoomFrame = memo(function RoomFrame({
 
   return (
     <PowerLevelsContextProvider value={powerLevels}>
-      <Box grow="Yes">
+      <Box grow="Yes" direction="Column" style={{ minHeight: 0, minWidth: 0 }}>
         {forumRoom && !pending ? (
           <ForumRoomView room={room} eventId={eventId} />
         ) : (
diff --git a/src/app/features/room/RoomTimeline.tsx b/src/app/features/room/RoomTimeline.tsx
index 81a35d3..ec28cb2 100644
--- a/src/app/features/room/RoomTimeline.tsx
+++ b/src/app/features/room/RoomTimeline.tsx
@@ -688,6 +688,17 @@ export const RoomTimeline = memo(function RoomTimeline({
       }),
     [mx, room, linkifyOpts, spoilerClickHandler, mentionClickHandler, useAuthentication]
   );
+  const jumboHtmlReactParserOptions = useMemo<HTMLReactParserOptions>(
+    () =>
+      getReactCustomHtmlParser(mx, room.roomId, {
+        linkifyOpts,
+        useAuthentication,
+        handleSpoilerClick: spoilerClickHandler,
+        handleMentionClick: mentionClickHandler,
+        jumbo: true,
+      }),
+    [mx, room, linkifyOpts, spoilerClickHandler, mentionClickHandler, useAuthentication]
+  );
   const parseMemberEvent = useMemberEventParser();
 
   const [timeline, setTimeline] = useState<Timeline>(() =>
@@ -1410,6 +1421,7 @@ export const RoomTimeline = memo(function RoomTimeline({
                 mediaAutoLoad={mediaAutoLoad}
                 urlPreview={showUrlPreview}
                 htmlReactParserOptions={htmlReactParserOptions}
+                jumboHtmlReactParserOptions={jumboHtmlReactParserOptions}
                 linkifyOpts={linkifyOpts}
                 outlineAttachment={messageLayout === MessageLayout.Bubble}
                 disabledEmbedPatterns={combinedEmbedFilters}
@@ -1518,6 +1530,7 @@ export const RoomTimeline = memo(function RoomTimeline({
                       mediaAutoLoad={mediaAutoLoad}
                       urlPreview={showUrlPreview}
                       htmlReactParserOptions={htmlReactParserOptions}
+                jumboHtmlReactParserOptions={jumboHtmlReactParserOptions}
                       linkifyOpts={linkifyOpts}
                       outlineAttachment={messageLayout === MessageLayout.Bubble}
                       disabledEmbedPatterns={combinedEmbedFilters}
diff --git a/src/app/features/room/ThreadView.tsx b/src/app/features/room/ThreadView.tsx
index 7d4511f..8ab1c96 100644
--- a/src/app/features/room/ThreadView.tsx
+++ b/src/app/features/room/ThreadView.tsx
@@ -212,6 +212,17 @@ export function ThreadView({ room, threadRootId }: ThreadViewProps) {
       }),
     [mx, room, linkifyOpts, spoilerClickHandler, mentionClickHandler, useAuthentication]
   );
+  const jumboHtmlReactParserOptions = useMemo<HTMLReactParserOptions>(
+    () =>
+      getReactCustomHtmlParser(mx, room.roomId, {
+        linkifyOpts,
+        useAuthentication,
+        handleSpoilerClick: spoilerClickHandler,
+        handleMentionClick: mentionClickHandler,
+        jumbo: true,
+      }),
+    [mx, room, linkifyOpts, spoilerClickHandler, mentionClickHandler, useAuthentication]
+  );
 
   const thread = room.getThread(threadRootId);
   const roomTimelineSet = room.getUnfilteredTimelineSet();
@@ -634,6 +645,7 @@ export function ThreadView({ room, threadRootId }: ThreadViewProps) {
                 mediaAutoLoad={mediaAutoLoad}
                 urlPreview={showUrlPreview}
                 htmlReactParserOptions={htmlReactParserOptions}
+                jumboHtmlReactParserOptions={jumboHtmlReactParserOptions}
                 linkifyOpts={linkifyOpts}
                 outlineAttachment={messageLayout === MessageLayout.Bubble}
                 disabledEmbedPatterns={combinedEmbedFilters}
@@ -650,6 +662,7 @@ export function ThreadView({ room, threadRootId }: ThreadViewProps) {
             mediaAutoLoad={mediaAutoLoad}
             urlPreview={showUrlPreview}
             htmlReactParserOptions={htmlReactParserOptions}
+            jumboHtmlReactParserOptions={jumboHtmlReactParserOptions}
             linkifyOpts={linkifyOpts}
             outlineAttachment={messageLayout === MessageLayout.Bubble}
             disabledEmbedPatterns={combinedEmbedFilters}
diff --git a/src/app/pages/client/direct/DirectLayout.tsx b/src/app/pages/client/direct/DirectLayout.tsx
index 78dd531..d417f5e 100644
--- a/src/app/pages/client/direct/DirectLayout.tsx
+++ b/src/app/pages/client/direct/DirectLayout.tsx
@@ -37,6 +37,7 @@ export function DirectLayout() {
         minHeight: 0,
         position: 'relative',
         display: 'flex',
+        flexDirection: 'column',
       }}
     >
       {keepHost && (
@@ -46,6 +47,7 @@ export function DirectLayout() {
             minWidth: 0,
             minHeight: 0,
             display: showingRoom ? 'flex' : 'none',
+            flexDirection: 'column',
             position: 'relative',
           }}
           aria-hidden={!showingRoom}
@@ -59,6 +61,7 @@ export function DirectLayout() {
           minWidth: 0,
           minHeight: 0,
           display: showingRoom ? 'none' : 'flex',
+          flexDirection: 'column',
           position: 'relative',
         }}
       >
diff --git a/src/app/pages/client/home/HomeLayout.tsx b/src/app/pages/client/home/HomeLayout.tsx
index 1a25c3d..ceaa388 100644
--- a/src/app/pages/client/home/HomeLayout.tsx
+++ b/src/app/pages/client/home/HomeLayout.tsx
@@ -34,6 +34,7 @@ export function HomeLayout() {
         minHeight: 0,
         position: 'relative',
         display: 'flex',
+        flexDirection: 'column',
       }}
     >
       {keepHost && (
@@ -43,6 +44,7 @@ export function HomeLayout() {
             minWidth: 0,
             minHeight: 0,
             display: showingRoom ? 'flex' : 'none',
+            flexDirection: 'column',
             position: 'relative',
           }}
           aria-hidden={!showingRoom}
@@ -56,6 +58,7 @@ export function HomeLayout() {
           minWidth: 0,
           minHeight: 0,
           display: showingRoom ? 'none' : 'flex',
+          flexDirection: 'column',
           position: 'relative',
         }}
       >
diff --git a/src/app/pages/client/space/SpaceRoomLayout.tsx b/src/app/pages/client/space/SpaceRoomLayout.tsx
index 8cdb619..bd71af2 100644
--- a/src/app/pages/client/space/SpaceRoomLayout.tsx
+++ b/src/app/pages/client/space/SpaceRoomLayout.tsx
@@ -46,6 +46,7 @@ export function SpaceRoomLayout() {
         minHeight: 0,
         position: 'relative',
         display: 'flex',
+        flexDirection: 'column',
       }}
     >
       {keepHost && (
@@ -55,6 +56,7 @@ export function SpaceRoomLayout() {
             minWidth: 0,
             minHeight: 0,
             display: showingRoom ? 'flex' : 'none',
+            flexDirection: 'column',
             position: 'relative',
           }}
           aria-hidden={!showingRoom}
@@ -68,6 +70,7 @@ export function SpaceRoomLayout() {
           minWidth: 0,
           minHeight: 0,
           display: showingRoom ? 'none' : 'flex',
+          flexDirection: 'column',
           position: 'relative',
         }}
       >
diff --git a/src/app/plugins/react-custom-html-parser.tsx b/src/app/plugins/react-custom-html-parser.tsx
index 8e1eb0d..5cc96c3 100644
--- a/src/app/plugins/react-custom-html-parser.tsx
+++ b/src/app/plugins/react-custom-html-parser.tsx
@@ -386,8 +386,10 @@ export const getReactCustomHtmlParser = (
     handleSpoilerClick?: ReactEventHandler<HTMLElement>;
     handleMentionClick?: ReactEventHandler<HTMLElement>;
     useAuthentication?: boolean;
+    jumbo?: boolean;
   }
 ): HTMLReactParserOptions => {
+  const jumbo = params.jumbo ?? false;
   const opts: HTMLReactParserOptions = {
     replace: (domNode) => {
       if (domNode instanceof Element && 'name' in domNode) {
@@ -443,6 +445,13 @@ export const getReactCustomHtmlParser = (
         }
 
         if (name === 'p') {
+          if (jumbo) {
+            return (
+              <p {...props} className={classNames(css.Paragraph, css.MarginSpaced)}>
+                {domToReact(children, opts)}
+              </p>
+            );
+          }
           return (
             <Text {...props} className={classNames(css.Paragraph, css.MarginSpaced)} size="Inherit">
               {domToReact(children, opts)}
@@ -561,9 +570,13 @@ export const getReactCustomHtmlParser = (
             // Drop presentational height/width so jumbo CSS can size freely
             const { height: _h, width: _w, ...imgProps } = props;
             return (
-              <span className={css.EmoticonBase}>
-                <span className={css.Emoticon()}>
-                  <AuthenticatedImg {...imgProps} className={css.EmoticonImg()} src={htmlSrc} />
+              <span className={jumbo ? css.EmoticonBaseJumbo : css.EmoticonBase}>
+                <span className={css.Emoticon({ jumbo })}>
+                  <AuthenticatedImg
+                    {...imgProps}
+                    className={css.EmoticonImg({ jumbo })}
+                    src={htmlSrc}
+                  />
                 </span>
               </span>
             );
@@ -577,7 +590,7 @@ export const getReactCustomHtmlParser = (
           !(domNode.parent && 'name' in domNode.parent && domNode.parent.name === 'code') &&
           !(domNode.parent && 'name' in domNode.parent && domNode.parent.name === 'a');
 
-        let jsx = scaleSystemEmoji(domNode.data);
+        let jsx = scaleSystemEmoji(domNode.data, jumbo);
 
         if (params.highlightRegex) {
           jsx = highlightText(params.highlightRegex, jsx);
diff --git a/src/app/utils/regex.ts b/src/app/utils/regex.ts
index 81c7341..706f31f 100644
--- a/src/app/utils/regex.ts
+++ b/src/app/utils/regex.ts
@@ -31,6 +31,15 @@ const JUMBO_IGNORE_CHARS_REG = /[\u200B-\u200D\uFEFF\u00AD\u2060\u00A0]/g;
 const ONLY_MX_EMOTICON_HTML_REG =
   /^(?:\s|<br\s*\/?>)*((?:<img\b[^>]*\bdata-mx-emoticon\b[^>]*\/?>)(?:\s|<br\s*\/?>)*){1,10}$/i;
 
+/** HTML that contains only custom Matrix emoticon images (no plain unicode body). */
+export const isMxEmoticonOnlyHtml = (html: string): boolean => {
+  const normalized = html
+    .replace(JUMBO_IGNORE_CHARS_REG, '')
+    .trim()
+    .replace(/(<br\s*\/?>\s*)+$/gi, '');
+  return normalized.length > 0 && ONLY_MX_EMOTICON_HTML_REG.test(normalized);
+};
+
 /**
  * True when a message is emoji/custom-emote only (Discord-style jumbo).
  * Strips zero-width chars and also accepts HTML that is only mx-emoticon imgs.
@@ -40,11 +49,7 @@ export const isJumboEmoji = (body: string, customBody?: string): boolean => {
   if (plain.length > 0 && JUMBO_EMOJI_REG.test(plain)) return true;
 
   if (typeof customBody === 'string') {
-    const html = customBody
-      .replace(JUMBO_IGNORE_CHARS_REG, '')
-      .trim()
-      .replace(/(<br\s*\/?>\s*)+$/gi, '');
-    if (html.length > 0 && ONLY_MX_EMOTICON_HTML_REG.test(html)) return true;
+    if (isMxEmoticonOnlyHtml(customBody)) return true;
   }
 
   return false;