diff --git a/geneit_app/src/App.tsx b/geneit_app/src/App.tsx
index c52a00c..779454d 100644
--- a/geneit_app/src/App.tsx
+++ b/geneit_app/src/App.tsx
@@ -1,4 +1,3 @@
-import { ThemeProvider, createTheme } from "@mui/material/styles";
 import React from "react";
 import { Route, Routes } from "react-router-dom";
 import "./App.css";
@@ -24,12 +23,6 @@ interface AuthContext {
 
 const AuthContextK = React.createContext<AuthContext | null>(null);
 
-const darkTheme = createTheme({
-  palette: {
-    mode: "dark", // TODO : switch back to light
-  },
-});
-
 /**
  * Core app
  */
@@ -42,37 +35,35 @@ export function App(): React.ReactElement {
   };
 
   return (
-    <ThemeProvider theme={darkTheme}>
-      <AuthContextK.Provider value={context}>
-        <Routes>
-          <Route path="delete_account" element={<DeleteAccountRoute />} />
+    <AuthContextK.Provider value={context}>
+      <Routes>
+        <Route path="delete_account" element={<DeleteAccountRoute />} />
 
-          {signedIn ? (
-            <Route path="*" element={<BaseAuthenticatedPage />}>
-              <Route path="" element={<FamiliesListRoute />} />
-              <Route path="profile" element={<ProfileRoute />} />
-              <Route path="family/:familyId/*" element={<BaseFamilyRoute />}>
-                <Route path="" element={<FamilyHomeRoute />} />
-                <Route path="*" element={<NotFoundRoute />} />
-              </Route>
+        {signedIn ? (
+          <Route path="*" element={<BaseAuthenticatedPage />}>
+            <Route path="" element={<FamiliesListRoute />} />
+            <Route path="profile" element={<ProfileRoute />} />
+            <Route path="family/:familyId/*" element={<BaseFamilyRoute />}>
+              <Route path="" element={<FamilyHomeRoute />} />
               <Route path="*" element={<NotFoundRoute />} />
             </Route>
-          ) : (
-            <Route path="*" element={<BaseLoginPage />}>
-              <Route path="" element={<LoginRoute />} />
-              <Route path="oidc_cb" element={<OIDCCbRoute />} />
-              <Route path="new-account" element={<NewAccountRoute />} />
-              <Route
-                path="password_forgotten"
-                element={<PasswordForgottenRoute />}
-              />
-              <Route path="reset_password" element={<ResetPasswordRoute />} />
-              <Route path="*" element={<NotFoundRoute />} />
-            </Route>
-          )}
-        </Routes>
-      </AuthContextK.Provider>
-    </ThemeProvider>
+            <Route path="*" element={<NotFoundRoute />} />
+          </Route>
+        ) : (
+          <Route path="*" element={<BaseLoginPage />}>
+            <Route path="" element={<LoginRoute />} />
+            <Route path="oidc_cb" element={<OIDCCbRoute />} />
+            <Route path="new-account" element={<NewAccountRoute />} />
+            <Route
+              path="password_forgotten"
+              element={<PasswordForgottenRoute />}
+            />
+            <Route path="reset_password" element={<ResetPasswordRoute />} />
+            <Route path="*" element={<NotFoundRoute />} />
+          </Route>
+        )}
+      </Routes>
+    </AuthContextK.Provider>
   );
 }
 
diff --git a/geneit_app/src/widgets/AlertDialogProvider.tsx b/geneit_app/src/context_providers/AlertDialogProvider.tsx
similarity index 100%
rename from geneit_app/src/widgets/AlertDialogProvider.tsx
rename to geneit_app/src/context_providers/AlertDialogProvider.tsx
diff --git a/geneit_app/src/widgets/ConfirmDialogProvider.tsx b/geneit_app/src/context_providers/ConfirmDialogProvider.tsx
similarity index 100%
rename from geneit_app/src/widgets/ConfirmDialogProvider.tsx
rename to geneit_app/src/context_providers/ConfirmDialogProvider.tsx
diff --git a/geneit_app/src/context_providers/DarkThemeProvider.tsx b/geneit_app/src/context_providers/DarkThemeProvider.tsx
new file mode 100644
index 0000000..b410df5
--- /dev/null
+++ b/geneit_app/src/context_providers/DarkThemeProvider.tsx
@@ -0,0 +1,50 @@
+import { ThemeProvider, createTheme } from "@mui/material/styles";
+import React from "react";
+import { PropsWithChildren } from "react";
+
+const localStorageKey = "dark-theme";
+
+const darkTheme = createTheme({
+  palette: {
+    mode: "dark",
+  },
+});
+
+const lightTheme = createTheme({
+  palette: {
+    mode: "light",
+  },
+});
+
+interface DarkThemeContext {
+  enabled: boolean;
+  setEnabled: (enabled: boolean) => void;
+}
+
+const DarkThemeContextK = React.createContext<DarkThemeContext | null>(null);
+
+export function DarkThemeProvider(p: PropsWithChildren): React.ReactElement {
+  const [enabled, setEnabled] = React.useState(
+    localStorage.getItem(localStorageKey) === "true"
+  );
+
+  return (
+    <DarkThemeContextK.Provider
+      value={{
+        enabled: enabled,
+        setEnabled(enabled) {
+          localStorage.setItem(localStorageKey, enabled ? "true" : "false");
+          setEnabled(enabled);
+        },
+      }}
+    >
+      <ThemeProvider theme={enabled ? darkTheme : lightTheme}>
+        {p.children}
+      </ThemeProvider>
+    </DarkThemeContextK.Provider>
+  );
+}
+
+export function useDarkTheme(): DarkThemeContext {
+  return React.useContext(DarkThemeContextK)!;
+}
diff --git a/geneit_app/src/widgets/SnackbarProvider.tsx b/geneit_app/src/context_providers/SnackbarProvider.tsx
similarity index 100%
rename from geneit_app/src/widgets/SnackbarProvider.tsx
rename to geneit_app/src/context_providers/SnackbarProvider.tsx
diff --git a/geneit_app/src/dialogs/CreateFamilyDialog.tsx b/geneit_app/src/dialogs/CreateFamilyDialog.tsx
index bd6eb44..98c41db 100644
--- a/geneit_app/src/dialogs/CreateFamilyDialog.tsx
+++ b/geneit_app/src/dialogs/CreateFamilyDialog.tsx
@@ -2,7 +2,7 @@ import React from "react";
 import { TextInputDialog } from "./TextInputDialog";
 import { ServerApi } from "../api/ServerApi";
 import { FamilyApi } from "../api/FamilyApi";
-import { useAlert } from "../widgets/AlertDialogProvider";
+import { useAlert } from "../context_providers/AlertDialogProvider";
 
 export function CreateFamilyDialog(p: {
   open: boolean;
diff --git a/geneit_app/src/dialogs/JoinFamilyDialog.tsx b/geneit_app/src/dialogs/JoinFamilyDialog.tsx
index 4f95dff..b61006e 100644
--- a/geneit_app/src/dialogs/JoinFamilyDialog.tsx
+++ b/geneit_app/src/dialogs/JoinFamilyDialog.tsx
@@ -2,7 +2,7 @@ import React from "react";
 import { TextInputDialog } from "./TextInputDialog";
 import { ServerApi } from "../api/ServerApi";
 import { FamilyApi, JoinFamilyResult } from "../api/FamilyApi";
-import { useAlert } from "../widgets/AlertDialogProvider";
+import { useAlert } from "../context_providers/AlertDialogProvider";
 
 export function JoinFamilyDialog(p: {
   open: boolean;
diff --git a/geneit_app/src/index.tsx b/geneit_app/src/index.tsx
index 1b2356e..a6dc414 100644
--- a/geneit_app/src/index.tsx
+++ b/geneit_app/src/index.tsx
@@ -11,10 +11,11 @@ import "@fontsource/roboto/400.css";
 import "@fontsource/roboto/500.css";
 import "@fontsource/roboto/700.css";
 import { BrowserRouter } from "react-router-dom";
-import { ConfirmDialogProvider } from "./widgets/ConfirmDialogProvider";
-import { AlertDialogProvider } from "./widgets/AlertDialogProvider";
+import { ConfirmDialogProvider } from "./context_providers/ConfirmDialogProvider";
+import { AlertDialogProvider } from "./context_providers/AlertDialogProvider";
 import { AsyncWidget } from "./widgets/AsyncWidget";
-import { SnackbarProvider } from "./widgets/SnackbarProvider";
+import { SnackbarProvider } from "./context_providers/SnackbarProvider";
+import { DarkThemeProvider } from "./context_providers/DarkThemeProvider";
 
 async function init() {
   try {
@@ -25,20 +26,22 @@ async function init() {
     root.render(
       <React.StrictMode>
         <BrowserRouter>
-          <AlertDialogProvider>
-            <ConfirmDialogProvider>
-              <SnackbarProvider>
-                <div style={{ height: "100vh" }}>
-                  <AsyncWidget
-                    loadKey={1}
-                    load={async () => await ServerApi.LoadConfig()}
-                    errMsg="Echec de la connexion au serveur pour la récupération de la configuration statique !"
-                    build={() => <App />}
-                  />
-                </div>
-              </SnackbarProvider>
-            </ConfirmDialogProvider>
-          </AlertDialogProvider>
+          <DarkThemeProvider>
+            <AlertDialogProvider>
+              <ConfirmDialogProvider>
+                <SnackbarProvider>
+                  <div style={{ height: "100vh" }}>
+                    <AsyncWidget
+                      loadKey={1}
+                      load={async () => await ServerApi.LoadConfig()}
+                      errMsg="Echec de la connexion au serveur pour la récupération de la configuration statique !"
+                      build={() => <App />}
+                    />
+                  </div>
+                </SnackbarProvider>
+              </ConfirmDialogProvider>
+            </AlertDialogProvider>
+          </DarkThemeProvider>
         </BrowserRouter>
       </React.StrictMode>
     );
diff --git a/geneit_app/src/routes/DeleteAccountRoute.tsx b/geneit_app/src/routes/DeleteAccountRoute.tsx
index 8f8fdab..d5293dc 100644
--- a/geneit_app/src/routes/DeleteAccountRoute.tsx
+++ b/geneit_app/src/routes/DeleteAccountRoute.tsx
@@ -3,9 +3,9 @@ import React from "react";
 import { Link, useLocation, useNavigate } from "react-router-dom";
 import { AuthApi } from "../api/AuthApi";
 import { DeleteAccountTokenInfo, UserApi } from "../api/UserApi";
-import { useAlert } from "../widgets/AlertDialogProvider";
+import { useAlert } from "../context_providers/AlertDialogProvider";
 import { AsyncWidget } from "../widgets/AsyncWidget";
-import { useConfirm } from "../widgets/ConfirmDialogProvider";
+import { useConfirm } from "../context_providers/ConfirmDialogProvider";
 
 export function DeleteAccountRoute(): React.ReactElement {
   const alert = useAlert();
diff --git a/geneit_app/src/routes/FamiliesListRoute.tsx b/geneit_app/src/routes/FamiliesListRoute.tsx
index d4e5f98..f775273 100644
--- a/geneit_app/src/routes/FamiliesListRoute.tsx
+++ b/geneit_app/src/routes/FamiliesListRoute.tsx
@@ -14,9 +14,9 @@ import React from "react";
 import { Family, FamilyApi } from "../api/FamilyApi";
 import { CreateFamilyDialog } from "../dialogs/CreateFamilyDialog";
 import { JoinFamilyDialog } from "../dialogs/JoinFamilyDialog";
-import { useAlert } from "../widgets/AlertDialogProvider";
+import { useAlert } from "../context_providers/AlertDialogProvider";
 import { AsyncWidget } from "../widgets/AsyncWidget";
-import { useConfirm } from "../widgets/ConfirmDialogProvider";
+import { useConfirm } from "../context_providers/ConfirmDialogProvider";
 import { RouterLink } from "../widgets/RouterLink";
 import { TimeWidget } from "../widgets/TimeWidget";
 
diff --git a/geneit_app/src/routes/ProfileRoute.tsx b/geneit_app/src/routes/ProfileRoute.tsx
index 43d368b..b0ea631 100644
--- a/geneit_app/src/routes/ProfileRoute.tsx
+++ b/geneit_app/src/routes/ProfileRoute.tsx
@@ -13,9 +13,9 @@ import {
 import React from "react";
 import { ServerApi } from "../api/ServerApi";
 import { ReplacePasswordResponse, User, UserApi } from "../api/UserApi";
-import { useAlert } from "../widgets/AlertDialogProvider";
+import { useAlert } from "../context_providers/AlertDialogProvider";
 import { useUser } from "../widgets/BaseAuthenticatedPage";
-import { useConfirm } from "../widgets/ConfirmDialogProvider";
+import { useConfirm } from "../context_providers/ConfirmDialogProvider";
 import { PasswordInput } from "../widgets/PasswordInput";
 import { formatDate } from "../widgets/TimeWidget";
 
diff --git a/geneit_app/src/widgets/BaseAuthenticatedPage.tsx b/geneit_app/src/widgets/BaseAuthenticatedPage.tsx
index 84d2a2b..6e5021a 100644
--- a/geneit_app/src/widgets/BaseAuthenticatedPage.tsx
+++ b/geneit_app/src/widgets/BaseAuthenticatedPage.tsx
@@ -14,6 +14,7 @@ import { AuthApi } from "../api/AuthApi";
 import { User, UserApi } from "../api/UserApi";
 import { AsyncWidget } from "./AsyncWidget";
 import { RouterLink } from "./RouterLink";
+import { DarkThemeButton } from "./DarkThemeButton";
 
 interface UserContext {
   user: User;
@@ -90,6 +91,8 @@ export function BaseAuthenticatedPage(): React.ReactElement {
                 </Typography>
 
                 <div>
+                  <DarkThemeButton />
+
                   <Button size="large" color="inherit">
                     {user!.name}
                   </Button>
diff --git a/geneit_app/src/widgets/BaseFamilyRoute.tsx b/geneit_app/src/widgets/BaseFamilyRoute.tsx
index 6c096d5..d909a8d 100644
--- a/geneit_app/src/widgets/BaseFamilyRoute.tsx
+++ b/geneit_app/src/widgets/BaseFamilyRoute.tsx
@@ -27,9 +27,9 @@ import { Outlet, useLocation, useParams } from "react-router-dom";
 import { Family, FamilyApi } from "../api/FamilyApi";
 import { AsyncWidget } from "./AsyncWidget";
 import { RouterLink } from "./RouterLink";
-import { useSnackbar } from "./SnackbarProvider";
-import { useConfirm } from "./ConfirmDialogProvider";
-import { useAlert } from "./AlertDialogProvider";
+import { useSnackbar } from "../context_providers/SnackbarProvider";
+import { useConfirm } from "../context_providers/ConfirmDialogProvider";
+import { useAlert } from "../context_providers/AlertDialogProvider";
 
 interface FamilyContext {
   family: Family;
diff --git a/geneit_app/src/widgets/BaseLoginpage.tsx b/geneit_app/src/widgets/BaseLoginpage.tsx
index e32b2ae..f3c6f70 100644
--- a/geneit_app/src/widgets/BaseLoginpage.tsx
+++ b/geneit_app/src/widgets/BaseLoginpage.tsx
@@ -8,6 +8,7 @@ import Paper from "@mui/material/Paper";
 import Typography from "@mui/material/Typography";
 import * as React from "react";
 import { Link, Outlet } from "react-router-dom";
+import { DarkThemeButton } from "./DarkThemeButton";
 
 function Copyright(props: any) {
   return (
@@ -64,6 +65,10 @@ export function BaseLoginPage() {
             alignItems: "center",
           }}
         >
+          <div style={{ position: "absolute", right: "10px", top: "5px" }}>
+            <DarkThemeButton />
+          </div>
+
           <Avatar sx={{ m: 1, bgcolor: "secondary.main" }}>
             <Icon path={mdiFamilyTree} size={1} />
           </Avatar>
diff --git a/geneit_app/src/widgets/DarkThemeButton.tsx b/geneit_app/src/widgets/DarkThemeButton.tsx
new file mode 100644
index 0000000..c9572c4
--- /dev/null
+++ b/geneit_app/src/widgets/DarkThemeButton.tsx
@@ -0,0 +1,19 @@
+import Brightness7Icon from "@mui/icons-material/Brightness7";
+import DarkModeIcon from "@mui/icons-material/DarkMode";
+import { IconButton, Tooltip } from "@mui/material";
+import { useDarkTheme } from "../context_providers/DarkThemeProvider";
+
+export function DarkThemeButton(): React.ReactElement {
+  const darkTheme = useDarkTheme();
+
+  return (
+    <Tooltip title="Activer / désactiver le mode sombre">
+      <IconButton
+        onClick={() => darkTheme.setEnabled(!darkTheme.enabled)}
+        style={{ color: "inherit" }}
+      >
+        {!darkTheme.enabled ? <DarkModeIcon /> : <Brightness7Icon />}
+      </IconButton>
+    </Tooltip>
+  );
+}