调整了多个页面的工具栏样式

frontend/src/components/MainLayout/AppHeader.css

@@ -8,6 +8,7 @@
   height: 64px;
   border-bottom: 1px solid var(--border-color);
   color: var(--text-color);
+  overflow: visible;
 }
 
 /* 左侧区域 */
@@ -55,6 +56,50 @@
   gap: 16px;
 }
 
+.workspace-header-brand {
+  position: relative;
+  height: 64px;
+  min-width: 360px;
+  padding-left: 70px;
+  padding-right: 36px;
+  display: inline-flex;
+  align-items: center;
+  gap: 14px;
+}
+
+.workspace-header-brand::before {
+  content: '';
+  position: absolute;
+  top: 0;
+  width: 1px;
+  height: 64px;
+  background: var(--border-color);
+}
+
+.workspace-header-brand::before {
+  left: 0;
+}
+
+.workspace-brand-icon {
+  font-size: 22px;
+  color: #6b7280;
+}
+
+.workspace-brand-title {
+  font-size: 18px;
+  font-weight: 600;
+  color: #4b5563;
+  white-space: nowrap;
+}
+
+body.dark .workspace-brand-title {
+  color: var(--text-color);
+}
+
+body.dark .workspace-brand-icon {
+  color: var(--text-color-secondary);
+}
+
 /* Icon Buttons */
 .header-icon-btn {
   display: flex;

frontend/src/components/MainLayout/AppHeader.jsx

@@ -10,7 +10,7 @@ import {
   NotificationOutlined,
   MoonOutlined,
   SunOutlined,
-  GlobalOutlined
+  AppstoreOutlined
 } from '@ant-design/icons'
 import useUserStore from '@/stores/userStore'
 import useNotificationStore from '@/stores/notificationStore'
@@ -151,7 +151,12 @@ function AppHeader({ collapsed, onToggle, showLogo = true }) {
           </div>
         </div>
       )}
-      {!showLogo && <div />} {/* Spacer if left is empty */}
+      {!showLogo && (
+        <div className="workspace-header-brand">
+          <AppstoreOutlined className="workspace-brand-icon" />
+          <span className="workspace-brand-title">NexDocus Workspace</span>
+        </div>
+      )}
 
       {/* 右侧：功能按钮 */}
       <div className="header-right">

frontend/src/components/ModernSidebar/ModernSidebar.css

@@ -30,39 +30,31 @@
   white-space: nowrap;
 }
 
-/* Collapse Trigger */
-.collapse-trigger {
+.sidebar-collapse-trigger {
   position: absolute;
-  right: -14px;
-  top: 28px;
-  width: 28px;
-  height: 28px;
-  background: var(--bg-color);
+  right: -13px;
+  top: 32px;
+  z-index: 20;
+  width: 26px;
+  height: 26px;
   border: 1px solid var(--border-color);
-  border-radius: 50%;
-  display: flex;
+  border-radius: 999px;
+  background: var(--header-bg);
+  color: #8a94a6;
+  display: inline-flex;
   align-items: center;
   justify-content: center;
+  box-shadow: 0 2px 8px rgba(0, 21, 41, 0.08);
   cursor: pointer;
-  z-index: 10;
-  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
-  color: var(--text-color-secondary);
-  font-size: 12px;
-  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
-  opacity: 0;
+  transform: translateY(-50%);
+  transition: all 0.2s;
+  font-size: 10px;
 }
 
-.modern-sidebar:hover .collapse-trigger,
-.collapse-trigger:focus {
-  opacity: 1;
-}
-
-.collapse-trigger:hover {
-  color: #fff;
-  background: #1677ff;
-  border-color: #1677ff;
-  box-shadow: 0 4px 12px rgba(22, 119, 255, 0.35);
-  transform: scale(1.1);
+.sidebar-collapse-trigger:hover {
+  color: #1677ff;
+  border-color: rgba(22, 119, 255, 0.28);
+  background: var(--header-bg);
 }
 
 /* Menu Area */

frontend/src/components/ModernSidebar/ModernSidebar.jsx

@@ -1,12 +1,10 @@
-import React, { useState } from 'react';
-import { Layout, Avatar, Tooltip, Button } from 'antd';
+import React from 'react';
+import { Layout, Avatar, Tooltip } from 'antd';
 import {
-  MenuUnfoldOutlined,
-  MenuFoldOutlined,
   LogoutOutlined,
   QuestionCircleOutlined,
   RightOutlined,
-  LeftOutlined
+  LeftOutlined,
 } from '@ant-design/icons';
 import './ModernSidebar.css';
 
@@ -81,13 +79,14 @@ const ModernSidebar = ({
         <div className="logo-container">
           {logo}
         </div>
-        {/* 折叠按钮 - 悬浮在边缘 */}
-        <div 
-          className="collapse-trigger"
+        <button
+          type="button"
+          className="sidebar-collapse-trigger"
           onClick={() => onCollapse && onCollapse(!collapsed)}
+          aria-label={collapsed ? '展开侧边栏' : '收起侧边栏'}
         >
           {collapsed ? <RightOutlined /> : <LeftOutlined />}
-        </div>
+        </button>
       </div>
 
       {/* 菜单列表区域 */}