diff --git a/memento-note/components/home-client.tsx b/memento-note/components/home-client.tsx
index d6b5402..bf564ce 100644
--- a/memento-note/components/home-client.tsx
+++ b/memento-note/components/home-client.tsx
@@ -11,7 +11,7 @@ import { NotesEditorialView } from '@/components/notes-editorial-view'
 import { MemoryEchoNotification } from '@/components/memory-echo-notification'
 import { NotebookSuggestionToast } from '@/components/notebook-suggestion-toast'
 import { Button } from '@/components/ui/button'
-import { Plus, ArrowUpDown, Search, Sparkles, FileText } from 'lucide-react'
+import { Plus, ArrowUpDown, Search, Sparkles, FileText, FolderOpen } from 'lucide-react'
 import { useNoteRefresh } from '@/context/NoteRefreshContext'
 import { useRefresh } from '@/lib/use-refresh'
 import { useReminderCheck } from '@/hooks/use-reminder-check'
@@ -21,6 +21,7 @@ import { cn } from '@/lib/utils'
 import { useLanguage } from '@/lib/i18n'
 import { useEditorUI } from '@/context/editor-ui-context'
 import { NoteHistoryModal } from '@/components/note-history-modal'
+import { CreateNotebookDialog } from '@/components/create-notebook-dialog'
 import { toast } from 'sonner'
 import { AnimatePresence, motion } from 'motion/react'
 
@@ -89,6 +90,7 @@ export function HomeClient({ initialNotes, initialSettings }: HomeClientProps) {
   const { shouldSuggest: shouldSuggestLabels, notebookId: suggestNotebookId, dismiss: dismissLabelSuggestion } = useAutoLabelSuggestion()
   const [autoLabelOpen, setAutoLabelOpen] = useState(false)
   const [summaryDialogOpen, setSummaryDialogOpen] = useState(false)
+  const [createSubNotebookOpen, setCreateSubNotebookOpen] = useState(false)
 
   useEffect(() => {
     if (shouldSuggestLabels && suggestNotebookId) {
@@ -424,6 +426,16 @@ export function HomeClient({ initialNotes, initialSettings }: HomeClientProps) {
                   <span>{t('notes.newNote') || 'Add Note'}</span>
                 </button>
 
+                {currentNotebook && (
+                  <button
+                    onClick={() => setCreateSubNotebookOpen(true)}
+                    className="flex items-center gap-2 text-[13px] text-foreground font-medium hover:opacity-70 transition-opacity"
+                  >
+                    <FolderOpen size={16} />
+                    <span>{t('notebook.createSubNotebook') || 'Nouveau sous-carnet'}</span>
+                  </button>
+                )}
+
                 {/* Inline search — toggles an input within the toolbar */}
                 {showInlineSearch ? (
                   <div className="flex items-center gap-2">
@@ -638,6 +650,13 @@ export function HomeClient({ initialNotes, initialSettings }: HomeClientProps) {
           notebookName={currentNotebook?.name}
         />
       )}
+      {searchParams.get('notebook') && (
+        <CreateNotebookDialog
+          open={createSubNotebookOpen}
+          onOpenChange={setCreateSubNotebookOpen}
+          parentNotebookId={searchParams.get('notebook')}
+        />
+      )}
     </div>
   )
 }
diff --git a/memento-note/components/sidebar.tsx b/memento-note/components/sidebar.tsx
index 1edbf50..4121e36 100644
--- a/memento-note/components/sidebar.tsx
+++ b/memento-note/components/sidebar.tsx
@@ -82,23 +82,30 @@ function SidebarCarnetItem({
   activeNoteId,
   onCarnetClick,
   onNoteClick,
+  onAddSubNotebook,
   children,
   isDragging,
   dragHandleProps,
+  depth = 0,
 }: {
-  carnet: { id: string; name: string; initial: string; isPrivate?: boolean }
+  carnet: { id: string; name: string; initial: string; isPrivate?: boolean; hasChildren?: boolean }
   isActive: boolean
   notes: { id: string; title: string }[]
   activeNoteId: string | null
   onCarnetClick: () => void
   onNoteClick: (noteId: string, carnetId: string) => void
+  onAddSubNotebook?: () => void
   children?: React.ReactNode
   isDragging?: boolean
   dragHandleProps?: React.HTMLAttributes<HTMLDivElement>
+  depth?: number
 }) {
   const { t } = useLanguage()
+  const [expanded, setExpanded] = useState(false)
+  const showContent = isActive || expanded
+
   return (
-    <div className={cn('space-y-1 transition-opacity', isDragging && 'opacity-40')}>
+    <div className={cn('transition-opacity', isDragging && 'opacity-40')}>
       <div className="relative group/carnet">
         <div
           {...dragHandleProps}
@@ -108,63 +115,78 @@ function SidebarCarnetItem({
           <GripVertical size={12} />
         </div>
 
-        <motion.button
-          whileHover={{ x: 4 }}
-          onClick={onCarnetClick}
+        <div
           className={cn(
-            'w-full flex items-center gap-3 px-4 py-3 rounded-xl transition-all duration-300 group',
+            'w-full flex items-center gap-3 px-4 py-2.5 rounded-xl transition-all duration-200 group cursor-pointer',
             isActive ? 'memento-active-nav' : 'hover:bg-white/40'
           )}
+          onClick={onCarnetClick}
         >
           <motion.div
-            animate={{ rotate: isActive ? 90 : 0 }}
-            className="text-muted-foreground"
+            animate={{ rotate: showContent ? 90 : 0 }}
+            className="text-muted-foreground shrink-0"
+            onClick={(e) => { e.stopPropagation(); setExpanded(v => !v) }}
           >
             <ChevronRight size={14} />
           </motion.div>
+
+          {depth > 0 && (
+            <div className="w-px h-4 bg-border/50 shrink-0" />
+          )}
+
           <div className={cn(
-            'w-8 h-8 rounded-full flex items-center justify-center text-sm font-medium border shrink-0',
+            'w-7 h-7 rounded-full flex items-center justify-center text-xs font-medium border shrink-0',
             isActive
               ? 'bg-foreground text-background border-foreground'
               : 'bg-white/60 text-foreground border-border'
           )}>
             {carnet.initial}
           </div>
-          <div className="flex-1 text-left min-w-0">
-            <div className="flex items-center gap-2">
-              <span className={cn(
-                'text-[13px] font-medium transition-colors truncate',
-                isActive ? 'text-foreground' : 'text-muted-foreground'
-              )}>
-                {carnet.name}
-              </span>
-              {carnet.isPrivate && <Lock size={10} className="text-muted-foreground shrink-0" />}
-            </div>
-          </div>
-        </motion.button>
+
+          <span className={cn(
+            'text-[13px] font-medium transition-colors truncate flex-1',
+            isActive ? 'text-foreground' : 'text-muted-foreground'
+          )}>
+            {carnet.name}
+          </span>
+
+          {carnet.isPrivate && <Lock size={10} className="text-muted-foreground shrink-0" />}
+
+          {onAddSubNotebook && (
+            <button
+              onClick={(e) => { e.stopPropagation(); onAddSubNotebook() }}
+              className="p-1 rounded-md text-muted-foreground/30 hover:text-foreground hover:bg-white/60 opacity-0 group-hover:opacity-100 transition-all shrink-0"
+              title={t('notebook.createSubNotebook') || 'Nouveau sous-carnet'}
+            >
+              <Plus size={12} />
+            </button>
+          )}
+        </div>
       </div>
 
       <AnimatePresence>
-        {isActive && (
+        {showContent && (
           <motion.div
             initial={{ height: 0, opacity: 0 }}
             animate={{ height: 'auto', opacity: 1 }}
             exit={{ height: 0, opacity: 0 }}
-            transition={{ duration: 0.4, ease: [0.23, 1, 0.32, 1] }}
-            className="overflow-hidden space-y-0.5"
+            transition={{ duration: 0.3, ease: [0.23, 1, 0.32, 1] }}
+            className="overflow-hidden"
           >
-            {children}
-            {notes.map(note => (
-              <NoteLink
-                key={note.id}
-                title={note.title}
-                isActive={activeNoteId === note.id}
-                onClick={() => onNoteClick(note.id, carnet.id)}
-              />
-            ))}
-            {notes.length === 0 && !children && (
-              <p className="pl-12 text-[11px] text-muted-foreground/50 py-2 italic font-light">{t('common.noResults')}</p>
-            )}
+            <div className={cn(depth > 0 && 'ml-4 border-l border-border/30 pl-2')}>
+              {children}
+              {notes.map(note => (
+                <NoteLink
+                  key={note.id}
+                  title={note.title}
+                  isActive={activeNoteId === note.id}
+                  onClick={() => onNoteClick(note.id, carnet.id)}
+                />
+              ))}
+              {notes.length === 0 && !children && (
+                <p className="pl-10 text-[11px] text-muted-foreground/50 py-2 italic font-light">{t('common.noResults')}</p>
+              )}
+            </div>
           </motion.div>
         )}
       </AnimatePresence>
@@ -446,14 +468,22 @@ export function Sidebar({ className, user }: { className?: string; user?: any })
                   <p className="text-[10px] font-bold text-muted-foreground tracking-widest uppercase">
                     {t('nav.notebooks')}
                   </p>
-                  <div className="relative">
+                  <div className="flex items-center gap-1">
                     <button
-                      onClick={() => setShowSortMenu(s => !s)}
-                      className="p-1 text-muted-foreground hover:text-foreground transition-colors rounded"
-                      title={t('sidebar.sortOrder')}
+                      onClick={() => { setCreateParentId(null); setIsCreateDialogOpen(true) }}
+                      className="p-1 text-muted-foreground hover:text-foreground hover:bg-white/40 transition-all rounded"
+                      title={t('notebook.create') || 'Nouveau carnet'}
                     >
-                      <ArrowUpDown size={12} />
+                      <Plus size={12} />
                     </button>
+                    <div className="relative">
+                      <button
+                        onClick={() => setShowSortMenu(s => !s)}
+                        className="p-1 text-muted-foreground hover:text-foreground transition-colors rounded"
+                        title={t('sidebar.sortOrder')}
+                      >
+                        <ArrowUpDown size={12} />
+                      </button>
                     <AnimatePresence>
                       {showSortMenu && (
                         <motion.div
@@ -479,6 +509,7 @@ export function Sidebar({ className, user }: { className?: string; user?: any })
                         </motion.div>
                       )}
                     </AnimatePresence>
+                    </div>
                   </div>
                 </div>
 
@@ -558,7 +589,7 @@ export function Sidebar({ className, user }: { className?: string; user?: any })
 
                 {/* Notebooks list — draggable */}
                 <div
-                  className="space-y-1"
+                  className="space-y-0.5"
                   onDrop={handleDrop}
                   onDragOver={(e) => e.preventDefault()}
                 >
@@ -573,12 +604,7 @@ export function Sidebar({ className, user }: { className?: string; user?: any })
                       <motion.div
                         key={notebook.id}
                         layout
-                        transition={{
-                          type: 'spring',
-                          stiffness: 300,
-                          damping: 30,
-                          mass: 0.8
-                        }}
+                        transition={{ type: 'spring', stiffness: 300, damping: 30, mass: 0.8 }}
                       >
                         <div
                           draggable
@@ -591,64 +617,45 @@ export function Sidebar({ className, user }: { className?: string; user?: any })
                               id: notebook.id,
                               name: notebook.name,
                               initial: notebook.name.charAt(0).toUpperCase(),
+                              hasChildren: children.length > 0,
                             }}
                             isActive={isExpanded}
                             notes={notes}
                             activeNoteId={currentNoteId}
                             onCarnetClick={() => handleCarnetClick(notebook.id)}
                             onNoteClick={handleNoteClick}
+                            onAddSubNotebook={() => {
+                              setCreateParentId(notebook.id)
+                              setIsCreateDialogOpen(true)
+                            }}
                             isDragging={isDragging}
+                            depth={0}
                           >
-                            {children.length > 0 && (
-                              <div className="pl-4 space-y-1 mt-1">
-                                {children.map(child => {
-                                  const childActive = currentNotebookId === child.id
-                                  const childNotes = notebookNotes[child.id] || []
-                                  return (
-                                    <div key={child.id}>
-                                      <SidebarCarnetItem
-                                        carnet={{
-                                          id: child.id,
-                                          name: child.name,
-                                          initial: child.name.charAt(0).toUpperCase(),
-                                        }}
-                                        isActive={childActive}
-                                        notes={childNotes}
-                                        activeNoteId={currentNoteId}
-                                        onCarnetClick={() => handleCarnetClick(child.id)}
-                                        onNoteClick={handleNoteClick}
-                                      />
-                                    </div>
-                                  )
-                                })}
-                                <button
-                                  onClick={() => {
-                                    setCreateParentId(notebook.id)
-                                    setIsCreateDialogOpen(true)
+                            {children.map(child => {
+                              const childActive = currentNotebookId === child.id
+                              const childNotes = notebookNotes[child.id] || []
+                              return (
+                                <SidebarCarnetItem
+                                  key={child.id}
+                                  carnet={{
+                                    id: child.id,
+                                    name: child.name,
+                                    initial: child.name.charAt(0).toUpperCase(),
                                   }}
-                                  className="w-full flex items-center gap-2 pl-12 pr-4 py-2 text-[11px] text-muted-foreground/50 hover:text-muted-foreground transition-colors"
-                                >
-                                  <Plus size={12} />
-                                  <span>{t('notebook.createSubNotebook') || 'Sous-carnet'}</span>
-                                </button>
-                              </div>
-                            )}
+                                  isActive={childActive}
+                                  notes={childNotes}
+                                  activeNoteId={currentNoteId}
+                                  onCarnetClick={() => handleCarnetClick(child.id)}
+                                  onNoteClick={handleNoteClick}
+                                  depth={1}
+                                />
+                              )
+                            })}
                           </SidebarCarnetItem>
                         </div>
                       </motion.div>
                     )
                   })}
-
-                  <button
-                    onClick={() => {
-                      setCreateParentId(null)
-                      setIsCreateDialogOpen(true)
-                    }}
-                    className="w-full mt-4 flex items-center gap-3 px-4 py-2 text-[13px] text-muted-foreground hover:text-foreground transition-colors font-medium rounded-lg hover:bg-white/40"
-                  >
-                    <Plus size={16} />
-                    <span>{t('notebook.create')}</span>
-                  </button>
                 </div>
               </motion.div>
             ) : (