diff --git a/frontend/src/App.vue b/frontend/src/App.vue
index 6e53a40..24921c1 100644
--- a/frontend/src/App.vue
+++ b/frontend/src/App.vue
@@ -1,68 +1,27 @@
 <template>
-  <div class="h-screen flex flex-col bg-gray-900">
+  <div class="h-screen flex flex-col bg-gray-950">
     <!-- Header compact -->
-    <header class="flex-shrink-0 bg-gray-800 border-b border-gray-700 px-4 py-2">
-      <div class="flex items-center justify-between">
-        <router-link to="/" class="text-lg font-semibold text-white hover:text-blue-400 transition-colors">
+    <header class="flex-shrink-0 bg-gray-900 border-b border-gray-700 px-6 py-2">
+      <div class="flex items-center justify-between gap-6">
+        <router-link to="/" class="text-lg font-semibold text-white hover:text-blue-400 transition-colors whitespace-nowrap">
           Plesna Gerance
           <span class="text-gray-400 font-normal text-sm ml-2">Extracteur de comptes rendus</span>
         </router-link>
-        
+
         <!-- Navigation -->
-        <nav class="flex items-center gap-3">
-          <router-link 
-            to="/" 
-            class="px-3 py-1.5 text-sm rounded transition-colors"
-            :class="$route.path === '/' ? 'bg-gray-700 text-white' : 'text-gray-400 hover:text-white'"
-          >
-            Accueil
-          </router-link>
-          
-          <router-link 
-            to="/documents" 
-            class="px-3 py-1.5 text-sm rounded transition-colors"
-            :class="$route.path === '/documents' ? 'bg-gray-700 text-white' : 'text-gray-400 hover:text-white'"
-          >
-            Documents
-          </router-link>
-          
-          <router-link 
-            to="/revenus" 
-            class="px-3 py-1.5 text-sm rounded transition-colors"
-            :class="$route.path === '/revenus' ? 'bg-gray-700 text-white' : 'text-gray-400 hover:text-white'"
-          >
-            Revenus
-          </router-link>
-          
+        <nav class="flex items-center gap-1">
           <router-link
-            to="/analytics"
-            class="px-3 py-1.5 text-sm rounded transition-colors"
-            :class="$route.path === '/analytics' ? 'bg-gray-700 text-white' : 'text-gray-400 hover:text-white'"
+            v-for="link in navLinks"
+            :key="link.to"
+            :to="link.to"
+            class="px-3 py-1.5 text-sm rounded-lg transition-colors"
+            :class="$route.path === link.to ? 'bg-gray-800 text-white' : 'text-gray-400 hover:text-white hover:bg-gray-800'"
           >
-            Depenses
-          </router-link>
-
-          <router-link
-            to="/ia"
-            class="px-3 py-1.5 text-sm rounded transition-colors"
-            :class="$route.path === '/ia' ? 'bg-gray-700 text-white' : 'text-gray-400 hover:text-white'"
-          >
-            IA
-          </router-link>
-
-          <router-link
-            to="/config"
-            class="px-3 py-1.5 text-sm rounded transition-colors"
-            :class="$route.path === '/config' ? 'bg-gray-700 text-white' : 'text-gray-400 hover:text-white'"
-          >
-            Config
+            {{ link.label }}
           </router-link>
 
           <!-- Import button with file input -->
-          <label 
-            class="px-3 py-1.5 text-sm rounded transition-colors cursor-pointer bg-blue-600/20 text-blue-400 hover:bg-blue-600 hover:text-white"
-            :class="$route.path === '/extract' ? 'bg-blue-600 text-white' : ''"
-          >
+          <label class="btn btn-primary ml-2 cursor-pointer">
             Importer un PDF
             <input
               ref="fileInput"
@@ -91,6 +50,15 @@ import { pendingFile } from './store'
 const router = useRouter()
 const fileInput = ref(null)
 
+const navLinks = [
+  { to: '/', label: 'Accueil' },
+  { to: '/documents', label: 'Documents' },
+  { to: '/revenus', label: 'Revenus' },
+  { to: '/analytics', label: 'Depenses' },
+  { to: '/ia', label: 'IA' },
+  { to: '/config', label: 'Config' }
+]
+
 function onFileSelect(e) {
   const file = e.target.files[0]
   if (file && file.name.toLowerCase().endsWith('.pdf')) {
diff --git a/frontend/src/style.css b/frontend/src/style.css
index 76c0273..87b18e0 100644
--- a/frontend/src/style.css
+++ b/frontend/src/style.css
@@ -2,22 +2,204 @@
 @tailwind components;
 @tailwind utilities;
 
-/* Custom scrollbar for JSON viewer */
+/*
+ * Design system : une seule palette sombre pour toute l'application.
+ *
+ *   gray-950  fond de page           gray-900  surfaces (cartes, header)
+ *   gray-800  sous-surfaces          gray-700  bordures
+ *   white / gray-400 / gray-500      textes principal / secondaire / tertiaire
+ *   blue-600                         accent
+ */
+@layer components {
+
+  /* --- Structure de page ------------------------------------------------ */
+
+  /* Conteneur racine d'une page : pleine largeur, marge laterale fixe. */
+  .page {
+    @apply flex-1 overflow-auto bg-gray-950 px-6 py-6;
+  }
+
+  /* Page sans defilement propre (split view type edition). */
+  .page-fixed {
+    @apply flex-1 flex flex-col overflow-hidden bg-gray-950;
+  }
+
+  .page-content {
+    @apply space-y-6;
+  }
+
+  .page-header {
+    @apply flex items-start justify-between gap-4;
+  }
+
+  .page-title {
+    @apply text-xl font-semibold text-white;
+  }
+
+  .page-subtitle {
+    @apply text-sm text-gray-400 mt-1;
+  }
+
+  /* --- Cartes ----------------------------------------------------------- */
+
+  .card {
+    @apply bg-gray-900 border border-gray-700 rounded-lg overflow-hidden;
+  }
+
+  .card-header {
+    @apply px-4 py-3 border-b border-gray-700 flex items-center justify-between gap-3;
+  }
+
+  .card-title {
+    @apply text-sm font-medium text-gray-300;
+  }
+
+  .card-body {
+    @apply p-4;
+  }
+
+  /* Bloc secondaire a l'interieur d'une carte. */
+  .subcard {
+    @apply bg-gray-800 border border-gray-700 rounded-lg;
+  }
+
+  /* --- Boutons ---------------------------------------------------------- */
+
+  .btn {
+    @apply inline-flex items-center justify-center gap-2 px-3 py-1.5 text-sm rounded-lg
+           transition-colors disabled:opacity-50 disabled:cursor-not-allowed;
+  }
+
+  .btn-primary {
+    @apply bg-blue-600 text-white hover:bg-blue-700;
+  }
+
+  .btn-secondary {
+    @apply bg-gray-800 text-gray-300 border border-gray-700 hover:bg-gray-700 hover:text-white;
+  }
+
+  .btn-ghost {
+    @apply text-gray-400 hover:text-white hover:bg-gray-800;
+  }
+
+  .btn-warning {
+    @apply bg-amber-600 text-white hover:bg-amber-700;
+  }
+
+  .btn-danger {
+    @apply bg-red-600 text-white hover:bg-red-700;
+  }
+
+  /* Variante compacte pour les actions dans les listes et tableaux. */
+  .btn-sm {
+    @apply px-2 py-1 text-xs gap-1.5;
+  }
+
+  /* --- Formulaires ------------------------------------------------------ */
+
+  .form-label {
+    @apply block text-sm font-medium text-gray-300 mb-1;
+  }
+
+  /* [color-scheme:dark] : les widgets natifs (calendrier, spinners) suivent le theme. */
+  .input {
+    @apply w-full bg-gray-950 border border-gray-700 rounded-lg px-3 py-2 text-sm text-white
+           placeholder-gray-500 focus:outline-none focus:border-blue-500 transition-colors
+           [color-scheme:dark];
+  }
+
+  select.input {
+    @apply cursor-pointer;
+  }
+
+  .form-hint {
+    @apply text-xs text-gray-500 mt-1;
+  }
+
+  /* --- Tableaux --------------------------------------------------------- */
+
+  /* Enveloppe a poser autour d'un <table> pour le defilement horizontal. */
+  .table-wrap {
+    @apply overflow-x-auto;
+  }
+
+  .table {
+    @apply w-full text-sm;
+  }
+
+  .table thead {
+    @apply bg-gray-800 border-b border-gray-700;
+  }
+
+  .table th {
+    @apply px-4 py-3 text-left text-xs font-medium text-gray-400 uppercase tracking-wider whitespace-nowrap;
+  }
+
+  .table tbody {
+    @apply divide-y divide-gray-800;
+  }
+
+  .table td {
+    @apply px-4 py-3 text-gray-300;
+  }
+
+  .table tbody tr {
+    @apply hover:bg-gray-800/50 transition-colors;
+  }
+
+  /* --- Badges ----------------------------------------------------------- */
+
+  .badge {
+    @apply inline-flex items-center gap-1 px-2 py-0.5 rounded text-xs font-medium;
+  }
+
+  .badge-neutral {
+    @apply bg-gray-700 text-gray-300;
+  }
+
+  .badge-info {
+    @apply bg-blue-500/15 text-blue-400;
+  }
+
+  .badge-success {
+    @apply bg-green-500/15 text-green-400;
+  }
+
+  .badge-warning {
+    @apply bg-amber-500/15 text-amber-400;
+  }
+
+  .badge-danger {
+    @apply bg-red-500/15 text-red-400;
+  }
+
+  /* --- Etats ------------------------------------------------------------ */
+
+  .empty-state {
+    @apply p-12 text-center text-gray-500;
+  }
+
+  .spinner {
+    @apply inline-block animate-spin rounded-full border-2 border-gray-700 border-t-blue-400;
+  }
+}
+
+/* Barres de defilement accordees au theme sombre. */
 .custom-scrollbar::-webkit-scrollbar {
   width: 8px;
   height: 8px;
 }
 
 .custom-scrollbar::-webkit-scrollbar-track {
-  background: #f1f5f9;
+  background: #111827; /* gray-900 */
   border-radius: 4px;
 }
 
 .custom-scrollbar::-webkit-scrollbar-thumb {
-  background: #cbd5e1;
+  background: #374151; /* gray-700 */
   border-radius: 4px;
 }
 
 .custom-scrollbar::-webkit-scrollbar-thumb:hover {
-  background: #94a3b8;
+  background: #4b5563; /* gray-600 */
 }