diff --git a/artifacts/cra-app/public/opengraph.jpg b/artifacts/cra-app/public/opengraph.jpg
index 2b60f32..4f199d5 100644
Binary files a/artifacts/cra-app/public/opengraph.jpg and b/artifacts/cra-app/public/opengraph.jpg differ
diff --git a/artifacts/cra-app/src/pages/not-found.tsx b/artifacts/cra-app/src/pages/not-found.tsx
index dba9f83..ef6215b 100644
--- a/artifacts/cra-app/src/pages/not-found.tsx
+++ b/artifacts/cra-app/src/pages/not-found.tsx
@@ -1,19 +1,25 @@
 import { Card, CardContent } from "@/components/ui/card";
 import { AlertCircle } from "lucide-react";
+import { Link } from "wouter";
+import { Button } from "@/components/ui/button";
 
 export default function NotFound() {
   return (
-    <div className="min-h-screen w-full flex items-center justify-center bg-gray-50">
+    <div className="min-h-screen w-full flex items-center justify-center bg-background">
       <Card className="w-full max-w-md mx-4">
         <CardContent className="pt-6">
-          <div className="flex mb-4 gap-2">
-            <AlertCircle className="h-8 w-8 text-red-500" />
-            <h1 className="text-2xl font-bold text-gray-900">404 Page Not Found</h1>
+          <div className="flex mb-4 gap-2 items-center">
+            <AlertCircle className="h-8 w-8 text-destructive" />
+            <h1 className="text-2xl font-bold">Page introuvable</h1>
           </div>
-
-          <p className="mt-4 text-sm text-gray-600">
-            Did you forget to add the page to the router?
+          <p className="mt-4 text-sm text-muted-foreground">
+            La page que vous cherchez n'existe pas ou a été déplacée.
           </p>
+          <Link href="/">
+            <Button variant="outline" className="mt-6">
+              Retour au tableau de bord
+            </Button>
+          </Link>
         </CardContent>
       </Card>
     </div>
diff --git a/artifacts/cra-app/src/pages/timesheet-detail.tsx b/artifacts/cra-app/src/pages/timesheet-detail.tsx
index 5406139..7707c08 100644
--- a/artifacts/cra-app/src/pages/timesheet-detail.tsx
+++ b/artifacts/cra-app/src/pages/timesheet-detail.tsx
@@ -33,6 +33,7 @@ import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogFooter } from "
 import { useToast } from "@/hooks/use-toast";
 import { formatMonthYear, STATUS_LABELS, STATUS_COLORS, cn } from "@/lib/utils";
 import { getDaysInMonth, isWeekend, format } from "date-fns";
+import { fr } from "date-fns/locale";
 
 type LocalEntry = {
   timesheetLineId: number;
@@ -91,7 +92,7 @@ export default function TimesheetDetailPage() {
         dateStr: format(date, "yyyy-MM-dd"),
         dayNum: i + 1,
         isWeekendDay: isWeekend(date),
-        dayName: format(date, "EE")
+        dayName: format(date, "EE", { locale: fr })
       };
     });