[Glitch] Add an explanation banner on switching to single column mode

Port 2c0eaf50f6 to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/features/ui/components/navigation_panel.jsx

@@ -29,6 +29,7 @@ const messages = defineMessages({
   about: { id: 'navigation_bar.about', defaultMessage: 'About' },
   search: { id: 'navigation_bar.search', defaultMessage: 'Search' },
   advancedInterface: { id: 'navigation_bar.advanced_interface', defaultMessage: 'Open in advanced web interface' },
+  openedInClassicInterface: { id: 'navigation_bar.opened_in_classic_interface', defaultMessage: 'Posts, accounts, and other specific pages are opened by default in the classic web interface.' },
   app_settings: { id: 'navigation_bar.app_settings', defaultMessage: 'App settings' },
 });
 
@@ -56,9 +57,13 @@ class NavigationPanel extends Component {
       <div className='navigation-panel'>
         {transientSingleColumn && (
           <div className='navigation-panel__logo'>
-            <a href={`/deck${location.pathname}`} className='button button--block'>
+            <div class='switch-to-advanced'>
+              {intl.formatMessage(messages.openedInClassicInterface)}
+              {" "}
+              <a href={`/deck${location.pathname}`} class='switch-to-advanced__toggle'>
                 {intl.formatMessage(messages.advancedInterface)}
               </a>
+            </div>
             <hr />
           </div>
         )}

app/javascript/flavours/glitch/styles/components/columns.scss

@@ -228,6 +228,22 @@ $ui-header-height: 55px;
   top: -48px;
 }
 
+.switch-to-advanced {
+  color: $classic-primary-color;
+  background-color: $classic-base-color;
+  padding: 15px;
+  border-radius: 4px;
+  margin-top: 4px;
+  margin-bottom: 12px;
+  font-size: 13px;
+  line-height: 18px;
+
+  .switch-to-advanced__toggle {
+    color: $ui-button-tertiary-color;
+    font-weight: bold;
+  }
+}
+
 .column-link {
   background: lighten($ui-base-color, 8%);
   color: $primary-text-color;