add classes for flex laout

src/client/js/components/Page/DisplaySwitcher.jsx

@@ -42,7 +42,7 @@ const DisplaySwitcher = (props) => {
               </div>
             </div>
 
-            <div>
+            <div className="flex-grow-1 flex-basis-0 mw-0">
               {pageUser && <UserInfo pageUser={pageUser} />}
               <Page />
             </div>

src/server/views/widget/page_content.html

@@ -40,7 +40,7 @@
   >
 {% endif %}
 
-<div class="flex-grow-1">
+<div class="flex-grow-1 flex-basis-0 mw-0">
   {% include 'page_alerts.html' %}
 
   <div id="display-switcher">