Issue #3319325 by mherchel, nod_, alexpott: Olivero: Mobile menu does not work when authenticated and BigPipe enabled(D10 only)

core/tests/Drupal/Nightwatch/Tests/Olivero/oliveroMobileMenuTest.js

@@ -172,4 +172,13 @@ module.exports = {
       .click('[href="#footer"]')
       .waitForElementNotVisible(headerNavSelector);
   },
+  'Verify mobile menu works when Big Pipe when authenticated': (browser) => {
+    browser.drupalInstallModule('big_pipe').drupalLoginAsAdmin(() => {
+      browser
+        .drupalRelativeURL('/')
+        .assert.not.visible(headerNavSelector)
+        .click(mobileNavButtonSelector)
+        .waitForElementVisible(headerNavSelector);
+    });
+  },
 };

core/themes/olivero/js/navigation.js

@@ -140,7 +140,7 @@
         const navButton = context.querySelector(
           '[data-drupal-selector="mobile-nav-button"]',
         );
-        const body = context.querySelector('body');
+        const body = document.body;
         const overlay = context.querySelector(
           '[data-drupal-selector="header-nav-overlay"]',
         );