chore: comment about CSS removal on route change to prevent visual gl…

…itches

- Added route change listener to delay CSS removal until route change is complete.
- Updated `CssTrackedApp` to ensure styles remain intact during transitions.

ilc/client/CssTrackedApp.js

@@ -4,6 +4,7 @@ export class CssTrackedApp {
     #originalApp;
     #cssLinkUri;
     #delayCssRemoval;
+    // used to prevent removing CSS immediately after unmounting
     #isRouteChanged = false;
     #routeChangeListener;
 
@@ -22,8 +23,10 @@ export class CssTrackedApp {
         this.#cssLinkUri = cssLink;
         this.#delayCssRemoval = delayCssRemoval;
 
-        // add route change listener for embedded apps
         if (!delayCssRemoval) {
+            // In an embedded app, removing CSS immediately after unmounting can cause visual glitches
+            // while a spinner is loading and the route is changing. Delaying CSS removal until the route
+            // change is complete ensures styles remain intact during the transition.
             this.#addRouteChangeListener();
         }
     }
@@ -128,6 +131,7 @@ export class CssTrackedApp {
     }
 
     #shouldDelayRemoval() {
+        // If the route is changing, we should delay CSS removal to prevent visual glitches.
         return this.#delayCssRemoval || this.#isRouteChanged;
     }