diff --git a/dash-apps/web-ambient/index.html b/dash-apps/web-ambient/index.html
index e7dec26..c1f93ff 100644
--- a/dash-apps/web-ambient/index.html
+++ b/dash-apps/web-ambient/index.html
@@ -613,6 +613,14 @@
 
     function receiveMessage(car) {
       lastCar = car;
+      // iOS sends darkMode in the message payload; Android sets data-theme via onCarStateUpdate.
+      // Only write on change: the MutationObserver below fires on every setAttribute call.
+      if (typeof car.darkMode === "boolean") {
+        const nextTheme = car.darkMode ? "dark" : "light";
+        if (document.documentElement.getAttribute("data-theme") !== nextTheme) {
+          document.documentElement.setAttribute("data-theme", nextTheme);
+        }
+      }
       const themeKey = activeThemeKey();
       const theme = THEME_STYLES[themeKey];
       const speed = Math.max(0, Math.round(Number(car.egoSpeed) || 0));
diff --git a/dash-apps/web-retro/index.html b/dash-apps/web-retro/index.html
index b1cd3fe..9fc1858 100644
--- a/dash-apps/web-retro/index.html
+++ b/dash-apps/web-retro/index.html
@@ -806,6 +806,13 @@
 }
 
 function receiveMessage(car) {
+  // iOS sends darkMode in the message payload; Android sets data-theme via onCarStateUpdate.
+  if (typeof car.darkMode === 'boolean') {
+    const nextTheme = car.darkMode ? 'dark' : 'light';
+    if (document.documentElement.getAttribute('data-theme') !== nextTheme) {
+      document.documentElement.setAttribute('data-theme', nextTheme);
+    }
+  }
   pendingCarState = car;
   if (renderFrame) return;
   renderFrame = window.requestAnimationFrame(flushCarState);