diff --git a/apps/staged/src/lib/features/layout/TopBar.svelte b/apps/staged/src/lib/features/layout/TopBar.svelte
index 9fdd4bb7f..94a83d0d0 100644
--- a/apps/staged/src/lib/features/layout/TopBar.svelte
+++ b/apps/staged/src/lib/features/layout/TopBar.svelte
@@ -11,12 +11,15 @@
   import { navigation, popDetailRoute } from './navigation.svelte';
   import { topBar } from './topBarState.svelte';
   import { viewport, watchViewport } from '../../shared/viewport.svelte';
+  import { getTrafficLightSpacerWidth, watchWindowChrome } from '../../shared/windowChrome.svelte';
   import { Button } from '$lib/components/ui/button';
 
   onMount(() => {
     const stopWatchingViewport = watchViewport();
+    const stopWatchingWindowChrome = watchWindowChrome();
     return () => {
       stopWatchingViewport();
+      stopWatchingWindowChrome();
     };
   });
 
@@ -33,10 +36,15 @@
   let hasTitle = $derived(
     !!topBar.title || !!topBar.subtitle || !!topBar.leading || !!topBar.badges
   );
+  let trafficLightSpacerWidth = $derived(getTrafficLightSpacerWidth(viewport.isMobile));
 </script>
 
 <!-- svelte-ignore a11y_no_static_element_interactions -->
-<div class="top-bar" onpointerdown={startDrag}>
+<div
+  class="top-bar"
+  style={`--traffic-light-spacer-width: ${trafficLightSpacerWidth}px`}
+  onpointerdown={startDrag}
+>
   <div class="traffic-light-spacer"></div>
   <div class="left-actions">
     {#if navigation.canGoBack}
@@ -112,7 +120,7 @@
   }
 
   .traffic-light-spacer {
-    width: 70px;
+    width: var(--traffic-light-spacer-width);
     flex-shrink: 0;
     align-self: stretch;
   }
@@ -214,11 +222,6 @@
     .top-bar {
       padding: 6px 8px;
     }
-
-    .traffic-light-spacer {
-      width: 58px;
-    }
-
     .title-content {
       max-width: min(46vw, 420px);
     }
diff --git a/apps/staged/src/lib/shared/windowChrome.svelte.ts b/apps/staged/src/lib/shared/windowChrome.svelte.ts
new file mode 100644
index 000000000..b37f9f851
--- /dev/null
+++ b/apps/staged/src/lib/shared/windowChrome.svelte.ts
@@ -0,0 +1,98 @@
+import { isTauri } from '../transport';
+
+const TRAFFIC_LIGHT_SPACER_WIDTH_PX = 70;
+
+function isMacPlatform(): boolean {
+  if (typeof navigator === 'undefined') return false;
+
+  return /mac/i.test(navigator.platform) || /Macintosh/i.test(navigator.userAgent);
+}
+
+export const windowChrome = $state({
+  isMac: isMacPlatform(),
+  isFullscreen: false,
+});
+
+let subscriberCount = 0;
+let stopBrowserResize: (() => void) | null = null;
+let stopTauriResize: (() => void) | null = null;
+let tauriResizeListenerGeneration = 0;
+let fullscreenSyncGeneration = 0;
+
+async function syncFullscreen() {
+  const generation = ++fullscreenSyncGeneration;
+
+  if (!isTauri) {
+    windowChrome.isFullscreen = false;
+    return;
+  }
+
+  try {
+    const { getCurrentWindow } = await import('@tauri-apps/api/window');
+    const isFullscreen = await getCurrentWindow().isFullscreen();
+    if (generation === fullscreenSyncGeneration && subscriberCount > 0) {
+      windowChrome.isFullscreen = isFullscreen;
+    }
+  } catch (error) {
+    console.warn('[windowChrome] Failed to sync fullscreen state:', error);
+    if (generation === fullscreenSyncGeneration && subscriberCount > 0) {
+      windowChrome.isFullscreen = false;
+    }
+  }
+}
+
+function syncWindowChrome() {
+  windowChrome.isMac = isMacPlatform();
+  void syncFullscreen();
+}
+
+function registerTauriResizeListener() {
+  if (!isTauri) return;
+
+  const generation = ++tauriResizeListenerGeneration;
+
+  void (async () => {
+    const { getCurrentWindow } = await import('@tauri-apps/api/window');
+    const unlisten = await getCurrentWindow().onResized(syncWindowChrome);
+
+    if (subscriberCount === 0 || generation !== tauriResizeListenerGeneration) {
+      unlisten();
+    } else {
+      stopTauriResize = unlisten;
+    }
+  })().catch((error) => {
+    console.warn('[windowChrome] Failed to watch resize events:', error);
+  });
+}
+
+export function getTrafficLightSpacerWidth(isMobile: boolean): number {
+  if (!isTauri || !windowChrome.isMac || isMobile || windowChrome.isFullscreen) return 0;
+  return TRAFFIC_LIGHT_SPACER_WIDTH_PX;
+}
+
+export function watchWindowChrome(): () => void {
+  if (typeof window === 'undefined') return () => {};
+
+  subscriberCount += 1;
+  syncWindowChrome();
+
+  if (subscriberCount === 1) {
+    const onResize = () => syncWindowChrome();
+    window.addEventListener('resize', onResize);
+    stopBrowserResize = () => window.removeEventListener('resize', onResize);
+    registerTauriResizeListener();
+  }
+
+  return () => {
+    subscriberCount = Math.max(0, subscriberCount - 1);
+
+    if (subscriberCount === 0) {
+      fullscreenSyncGeneration += 1;
+      tauriResizeListenerGeneration += 1;
+      stopBrowserResize?.();
+      stopTauriResize?.();
+      stopBrowserResize = null;
+      stopTauriResize = null;
+    }
+  };
+}