Fix overflow issue on mobile

app/soapbox/features/chats/components/chat-page/components/welcome.tsx

@@ -36,7 +36,7 @@ const Welcome = () => {
   };
 
   return (
-    <Stack className='py-20 px-4 sm:px-0' data-testid='chats-welcome'>
+    <Stack className='py-20 px-4 sm:px-0 h-full overflow-y-auto' data-testid='chats-welcome'>
       <div className='w-full sm:w-3/5 xl:w-2/5 mx-auto mb-10'>
         <Text align='center' weight='bold' className='mb-6 text-2xl md:text-3xl leading-8'>
           {intl.formatMessage(messages.title, { br: <br /> })}