Update Page.jsx

src/client/js/components/Page.jsx

@@ -129,7 +129,7 @@ class Page extends React.Component {
 
   render() {
     const { appContainer, pageContainer } = this.props;
-    const isMobile = appContainer.isMobile;
+    const { isMobile } = appContainer;
     const isLoggedIn = appContainer.currentUser != null;
     const { markdown } = pageContainer.state;