fix: reduce macOS popup compositing cost

src/main.tsx

@@ -10,6 +10,11 @@ import './styles/globals.css';
 import 'katex/dist/katex.min.css';
 import { initializeDefaultTransports } from './lib/api-client';
 
+const platform = window.electron?.platform;
+if (platform) {
+  document.documentElement.dataset.platform = platform;
+}
+
 initializeDefaultTransports();
 
 ReactDOM.createRoot(document.getElementById('root')!).render(

src/styles/globals.css

@@ -219,6 +219,48 @@
   backdrop-filter: blur(18px) saturate(135%);
 }
 
+/* Chromium's backdrop sampling is disproportionately expensive for transient
+ * layers in macOS Electron windows. Keep the optimization platform-scoped so
+ * the shared materials remain unchanged elsewhere. */
+html[data-platform='darwin'] :is(
+  [role='dialog'],
+  [role='alertdialog'],
+  [role='menu'],
+  [role='listbox'],
+  [role='tooltip'],
+  .fixed.inset-0
+),
+html[data-platform='darwin'] :is(
+  [role='dialog'],
+  [role='alertdialog'],
+  [role='menu'],
+  [role='listbox'],
+  [role='tooltip'],
+  .fixed.inset-0
+) .glass-surface {
+  -webkit-backdrop-filter: none !important;
+  backdrop-filter: none !important;
+}
+
+html[data-platform='darwin'] :is(
+  [role='dialog'],
+  [role='alertdialog'],
+  [role='menu'],
+  [role='listbox'],
+  [role='tooltip'],
+  .fixed.inset-0
+).glass-surface,
+html[data-platform='darwin'] :is(
+  [role='dialog'],
+  [role='alertdialog'],
+  [role='menu'],
+  [role='listbox'],
+  [role='tooltip'],
+  .fixed.inset-0
+) .glass-surface {
+  background-color: hsl(var(--background));
+}
+
 /* Sidebar material: keep the rail visibly white while allowing a restrained
  * amount of the canvas to show through. A low white alpha reads as gray over
  * the transparent native window material, so the light surface needs to stay