diff --git a/src/App.jsx b/src/App.jsx
index 6834635..f08b0b3 100644
--- a/src/App.jsx
+++ b/src/App.jsx
@@ -1,11 +1,42 @@
-import React from "react";
+import React, { useEffect, useState } from "react";
 import TopBar from "./components/Layout/TopBar";
 import MapView from "./components/Map/MapView";
 
+const THEME_KEY = "sociowire:theme";
+
 export default function App() {
+  const [theme, setTheme] = useState("dark");
+
+  // charge le thème depuis le localStorage au démarrage
+  useEffect(() => {
+    if (typeof window === "undefined") return;
+    try {
+      const saved = localStorage.getItem(THEME_KEY);
+      if (saved === "dark" || saved === "blue" || saved === "light") {
+        setTheme(saved);
+        document.body.setAttribute("data-theme", saved);
+      } else {
+        document.body.setAttribute("data-theme", "dark");
+      }
+    } catch {
+      document.body.setAttribute("data-theme", "dark");
+    }
+  }, []);
+
+  // applique le thème + sauvegarde
+  useEffect(() => {
+    if (typeof window === "undefined") return;
+    try {
+      document.body.setAttribute("data-theme", theme);
+      localStorage.setItem(THEME_KEY, theme);
+    } catch {
+      // ignore
+    }
+  }, [theme]);
+
   return (
     <div className="app-root">
-      <TopBar />
+      <TopBar theme={theme} onChangeTheme={setTheme} />
       <div className="main-shell">
         <div className="map-shell">
           <MapView />
diff --git a/src/components/Layout/TopBar.jsx b/src/components/Layout/TopBar.jsx
index 1c021d6..56e11a6 100644
--- a/src/components/Layout/TopBar.jsx
+++ b/src/components/Layout/TopBar.jsx
@@ -1,14 +1,39 @@
 import React from "react";
 
-export default function TopBar() {
+const THEME_LABELS = {
+  dark: "Dark",
+  blue: "Blue",
+  light: "Light",
+};
+
+export default function TopBar({ theme = "dark", onChangeTheme }) {
   return (
     <header className="topbar">
       <div className="logo-circle">SW</div>
+
       <div className="title-block">
         <div className="main-title">SOCIOWIRE.com</div>
         <div className="sub-title">Wired to life</div>
       </div>
-      <button className="btn-primary">Login</button>
+
+      <div className="topbar-right">
+        <div className="theme-switch">
+          {["dark", "blue", "light"].map((t) => (
+            <button
+              key={t}
+              type="button"
+              className={
+                "theme-dot" + (theme === t ? " theme-dot-active" : "")
+              }
+              title={THEME_LABELS[t]}
+              onClick={() => onChangeTheme && onChangeTheme(t)}
+            >
+              {THEME_LABELS[t][0]}
+            </button>
+          ))}
+        </div>
+        <button className="btn-primary">Login</button>
+      </div>
     </header>
   );
 }
diff --git a/src/main.jsx b/src/main.jsx
index 163bce2..faff4e8 100644
--- a/src/main.jsx
+++ b/src/main.jsx
@@ -9,7 +9,8 @@ import "./styles/map.css";
 import "./styles/markers.css";
 import "./styles/popup.css";
 import "./styles/overlays.css";
-import "./styles/posts.css";   // Sociowall + chat
+import "./styles/posts.css";
+import "./styles/theme.css";
 
 ReactDOM.createRoot(document.getElementById("root")).render(
   <React.StrictMode>
diff --git a/src/styles/layout.css b/src/styles/layout.css
index c76c9b9..a40c6f9 100644
--- a/src/styles/layout.css
+++ b/src/styles/layout.css
@@ -6,18 +6,19 @@
   flex-direction: column;
 }
 
+/* plus aucun espace entre la topbar et la carte */
 .main-shell {
   flex: 1;
   display: flex;
-  padding: 0.6rem;
+  padding: 0;
 }
 
-/* Conteneur de la carte plein écran */
+/* Conteneur de la carte plein écran collé aux bords */
 .map-shell {
   position: relative;
   flex: 1;
-  border-radius: 1rem;
+  border-radius: 0;
   overflow: hidden;
-  border: 1px solid #1f2937;
+  border: none;
   background: #020617;
 }
diff --git a/src/styles/theme.css b/src/styles/theme.css
new file mode 100644
index 0000000..d8cc270
--- /dev/null
+++ b/src/styles/theme.css
@@ -0,0 +1,89 @@
+/* ==========================================
+   THEME SYSTEM — body[data-theme="..."]
+   Trois thèmes : dark (par défaut), blue, light
+   ========================================== */
+
+/* Thème noir (par défaut) */
+body[data-theme="dark"] {
+  background: #050816;
+  color: #ffffff;
+}
+
+/* ===================== BLUE ===================== */
+
+body[data-theme="blue"] .sociowall-panel,
+body[data-theme="blue"] .chat-panel,
+body[data-theme="blue"] .post-card,
+body[data-theme="blue"] .post-pin--expanded .post-card,
+body[data-theme="blue"] .post-pin--compact .post-pin-bubble,
+body[data-theme="blue"] .popup-post-card {
+  background: rgba(12, 20, 60, 0.96);
+  border-color: rgba(96, 165, 250, 0.95);
+}
+
+body[data-theme="blue"] .chip-round,
+body[data-theme="blue"] .chip-pill,
+body[data-theme="blue"] .chip-egg,
+body[data-theme="blue"] .chip-hex {
+  background: rgba(10, 22, 60, 0.96);
+  border-color: rgba(96, 165, 250, 0.9);
+}
+
+body[data-theme="blue"] .chip-selected,
+body[data-theme="blue"] .chip-egg-active {
+  background: linear-gradient(135deg, #1d4ed8, #38bdf8);
+  border-color: #bfdbfe;
+}
+
+/* ===================== LIGHT ===================== */
+
+body[data-theme="light"] {
+  background: #e5e7eb;
+  color: #111827;
+}
+
+/* panneaux principaux clairs */
+body[data-theme="light"] .sociowall-panel,
+body[data-theme="light"] .chat-panel,
+body[data-theme="light"] .post-card,
+body[data-theme="light"] .post-pin--expanded .post-card,
+body[data-theme="light"] .popup-post-card {
+  background: rgba(248, 250, 252, 0.97);
+  border-color: rgba(148, 163, 184, 0.9);
+  color: #111827;
+}
+
+/* petits marqueurs compacts */
+body[data-theme="light"] .post-pin--compact .post-pin-bubble {
+  background: rgba(255, 255, 255, 0.96);
+  border-color: rgba(148, 163, 184, 0.9);
+  color: #0f172a;
+}
+
+/* chips claires */
+body[data-theme="light"] .chip-round,
+body[data-theme="light"] .chip-pill,
+body[data-theme="light"] .chip-egg,
+body[data-theme="light"] .chip-hex {
+  background: rgba(255, 255, 255, 0.98);
+  border-color: rgba(148, 163, 184, 0.9);
+  color: #111827;
+}
+
+body[data-theme="light"] .chip-selected,
+body[data-theme="light"] .chip-egg-active {
+  background: linear-gradient(135deg, #38bdf8, #0ea5e9);
+  border-color: #0ea5e9;
+  color: #0f172a;
+}
+
+/* topbar clair */
+body[data-theme="light"] .topbar {
+  background: #f9fafb;
+  border-bottom-color: #e5e7eb;
+}
+
+body[data-theme="light"] .main-title,
+body[data-theme="light"] .sub-title {
+  color: #0f172a;
+}
diff --git a/src/styles/topbar.css b/src/styles/topbar.css
index 79e9a2a..4b8848f 100644
--- a/src/styles/topbar.css
+++ b/src/styles/topbar.css
@@ -36,6 +36,40 @@
   opacity: 0.7;
 }
 
+/* bloc de droite : thèmes + bouton login */
+.topbar-right {
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+}
+
+/* petits boutons de thème (D / B / L) */
+.theme-switch {
+  display: flex;
+  gap: 0.25rem;
+}
+
+.theme-dot {
+  width: 22px;
+  height: 22px;
+  border-radius: 999px;
+  border: 1px solid #4b5563;
+  background: #020617;
+  color: #e5e7eb;
+  font-size: 0.65rem;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  padding: 0;
+  cursor: pointer;
+}
+
+.theme-dot-active {
+  border-color: #facc15;
+  box-shadow: 0 0 10px rgba(250, 204, 21, 0.7);
+}
+
+/* bouton Login */
 .btn-primary {
   padding: 0.25rem 0.7rem;
   font-size: 0.75rem;