diff --git a/package.json b/package.json
index 6268bcdb..6e068ca4 100644
--- a/package.json
+++ b/package.json
@@ -8,12 +8,12 @@
     "start:main": "wait-on http-get://localhost:4200/ && npm run build:main:development && electron --nolazy --inspect-brk=9229 .",
     "start:renderer": "cross-env UCAP_ENV_RUNTIME=ELECTRON ng serve -c renderer-development",
     "start:browser": "cross-env UCAP_ENV_RUNTIME=BROWSER ng serve -c browser-development -o",
-    "run": "electron .",
     "build": "npm-run-all -p build:renderer build:main:production",
     "build:renderer": "cross-env NODE_ENV=production ng build -c renderer-development --base-href ./",
     "build:browser": "cross-env UCAP_ENV_RUNTIME=BROWSER ng build -c browser-development",
     "build:main:development": "cross-env NODE_ENV=development TS_NODE_PROJECT='./config/tsconfig.webpack.json' parallel-webpack --config=config/main.webpack.config.ts",
     "build:main:production": "cross-env NODE_ENV=production TS_NODE_PROJECT='./config/tsconfig.webpack.json' NODE_OPTIONS='--max_old_space_size=4096' parallel-webpack --config=config/main.webpack.config.ts",
+    "electron:local": "electron .",
     "electron:windows": "electron-builder build --windows",
     "electron:mac": "electron-builder build --mac",
     "electron:linux": "electron-builder build --linux",
diff --git a/projects/ucap-webmessenger-ui-group/src/lib/components/expansion-panel.component.html b/projects/ucap-webmessenger-ui-group/src/lib/components/expansion-panel.component.html
index bb20f3da..73c887e5 100644
--- a/projects/ucap-webmessenger-ui-group/src/lib/components/expansion-panel.component.html
+++ b/projects/ucap-webmessenger-ui-group/src/lib/components/expansion-panel.component.html
@@ -23,7 +23,7 @@
     </mat-tree-node>
     <!-- This is the tree node template for expandable nodes -->
     <mat-tree-node
-      *matTreeNodeDef="let node; when: hasChild"
+      *matTreeNodeDef="let node; when: isHeader"
       class="tree-node-frame"
       style="height: 80px;"
     >
diff --git a/projects/ucap-webmessenger-ui-group/src/lib/components/expansion-panel.component.ts b/projects/ucap-webmessenger-ui-group/src/lib/components/expansion-panel.component.ts
index 553efb6e..35b24202 100644
--- a/projects/ucap-webmessenger-ui-group/src/lib/components/expansion-panel.component.ts
+++ b/projects/ucap-webmessenger-ui-group/src/lib/components/expansion-panel.component.ts
@@ -8,7 +8,8 @@ import {
   ContentChild,
   TemplateRef,
   AfterViewInit,
-  ChangeDetectorRef
+  ChangeDetectorRef,
+  OnDestroy
 } from '@angular/core';
 
 import { ucapAnimations } from '@ucap-webmessenger/ui';
@@ -25,6 +26,8 @@ import { NGXLogger } from 'ngx-logger';
 import { VirtualScrollTreeFlatDataSource } from '@ucap-webmessenger/ui';
 import { FlatTreeControl } from '@angular/cdk/tree';
 import { CdkVirtualScrollViewport } from '@angular/cdk/scrolling';
+import { fromEvent, Subject } from 'rxjs';
+import { debounceTime, takeUntil } from 'rxjs/operators';
 
 enum NodeType {
   None = 'None',
@@ -55,7 +58,8 @@ interface FlatNode {
   styleUrls: ['./expansion-panel.component.scss'],
   animations: ucapAnimations
 })
-export class ExpansionPanelComponent implements OnInit, AfterViewInit {
+export class ExpansionPanelComponent
+  implements OnInit, OnDestroy, AfterViewInit {
   @Input()
   set myProfileInfo(userInfo: UserInfo) {
     if (!userInfo) {
@@ -156,6 +160,8 @@ export class ExpansionPanelComponent implements OnInit, AfterViewInit {
   @ViewChild('cvsvGroup', { static: false })
   cvsvGroup: CdkVirtualScrollViewport;
 
+  private readonly destroySubject = new Subject();
+
   NodeType = NodeType;
 
   profileNodes: GroupNode[] = [];
@@ -185,7 +191,7 @@ export class ExpansionPanelComponent implements OnInit, AfterViewInit {
           countOfChildren:
             !!node.children && node.children.length > 0
               ? node.children.length
-              : undefined,
+              : 0,
           userInfo: node.userInfo,
           groupDetail: node.groupDetail
         };
@@ -201,13 +207,23 @@ export class ExpansionPanelComponent implements OnInit, AfterViewInit {
     );
   }
 
-  ngOnInit() {}
+  ngOnInit() {
+    fromEvent(window, 'resize')
+      .pipe(debounceTime(10), takeUntil(this.destroySubject))
+      .subscribe(() => this.cvsvGroup.checkViewportSize());
+  }
+
+  ngOnDestroy(): void {
+    this.destroySubject.next();
+    this.destroySubject.complete();
+  }
 
   ngAfterViewInit(): void {
     this.dataSource.cdkVirtualScrollViewport = this.cvsvGroup;
   }
 
-  hasChild = (_: number, node: FlatNode) => node.expandable;
+  // hasChild = (_: number, node: FlatNode) => node.expandable;
+  isHeader = (_: number, node: FlatNode) => 0 === node.level;
 
   expandMore() {
     this.groupAccordion.openAll();