DEV: Add mainOutletModifierClasses for chat main outlet

The main outlet needs different styles based on the route,
and whether the sidebar is expanded.

plugins/chat/assets/javascripts/discourse/controllers/chat.js

@@ -4,6 +4,7 @@ import { inject as service } from "@ember/service";
 export default class ChatController extends Controller {
   @service chat;
   @service chatStateManager;
+  @service router;
 
   get shouldUseChatSidebar() {
     if (this.site.mobileView) {
@@ -20,4 +21,21 @@ export default class ChatController extends Controller {
   get shouldUseCoreSidebar() {
     return this.siteSettings.navigation_menu === "sidebar";
   }
+
+  get mainOutletModifierClasses() {
+    let modifierClasses = [];
+
+    if (this.chatStateManager.isSidePanelExpanded) {
+      modifierClasses.push("has-side-panel-expanded");
+    }
+
+    if (
+      !this.router.currentRouteName.startsWith("chat.channel.info") &&
+      !this.router.currentRouteName.startsWith("chat.browse")
+    ) {
+      modifierClasses.push("chat-blah");
+    }
+
+    return modifierClasses.join(" ");
+  }
 }

plugins/chat/assets/javascripts/discourse/templates/chat.hbs

@@ -21,7 +21,7 @@
       id="main-chat-outlet"
       class={{concat-class
         "main-chat-outlet"
-        (if this.chatStateManager.isSidePanelExpanded "has-side-panel-expanded")
+        this.mainOutletModifierClasses
       }}
     >
       {{outlet}}