Make left navigation items selectable

patterns/left-navigation.html

@@ -87,6 +87,14 @@
         setMenuState(menu.hidden);
       });
 
+      menu.querySelectorAll('.sg-tab-button').forEach((button) => {
+        button.addEventListener('click', () => {
+          menu.querySelectorAll('.sg-tab-button').forEach((otherButton) => {
+            otherButton.setAttribute('aria-selected', String(otherButton === button));
+          });
+        });
+      });
+
       syncMode();
       mediaQuery.addEventListener('change', syncMode);
     })();