fix lint error

src/client/js/app.jsx

@@ -35,7 +35,6 @@ import UserPictureList from './components/User/UserPictureList';
 import TableOfContents from './components/TableOfContents';
 
 import UserGroupDetailPage from './components/Admin/UserGroupDetail/UserGroupDetailPage';
-import CustomCssEditor from './components/Admin/CustomCssEditor';
 import CustomScriptEditor from './components/Admin/CustomScriptEditor';
 import CustomHeaderEditor from './components/Admin/CustomHeaderEditor';
 import MarkdownSetting from './components/Admin/MarkdownSetting/MarkDownSetting';