fix: Sticky offset in nested AppLayout

pages/app-layout/multi-layout-with-table-sticky-header.page.tsx

@@ -0,0 +1,58 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+import React from 'react';
+
+import AppLayout from '~components/app-layout';
+import Button from '~components/button';
+import Header from '~components/header';
+import Table from '~components/table';
+
+import { generateItems, Instance } from '../table/generate-data';
+import { columnsConfig } from '../table/shared-configs';
+import ScreenshotArea from '../utils/screenshot-area';
+import { Breadcrumbs, Navigation } from './utils/content-blocks';
+import { Tools } from './utils/content-blocks';
+import labels from './utils/labels';
+import * as toolsContent from './utils/tools-content';
+
+const items = generateItems(100);
+
+export default function () {
+  return (
+    <ScreenshotArea gutters={false}>
+      <AppLayout
+        data-testid="main-layout"
+        ariaLabels={labels}
+        navigation={<Navigation />}
+        toolsHide={true}
+        disableContentPaddings={true}
+        content={
+          <AppLayout
+            data-testid="secondary-layout"
+            ariaLabels={labels}
+            breadcrumbs={<Breadcrumbs />}
+            navigationHide={true}
+            content={
+              <Table<Instance>
+                header={
+                  <Header
+                    variant="awsui-h1-sticky"
+                    description="Demo page with footer"
+                    actions={<Button variant="primary">Create</Button>}
+                  >
+                    Sticky Scrollbar Example
+                  </Header>
+                }
+                stickyHeader={true}
+                variant="full-page"
+                columnDefinitions={columnsConfig}
+                items={items}
+              />
+            }
+            tools={<Tools>{toolsContent.long}</Tools>}
+          />
+        }
+      />
+    </ScreenshotArea>
+  );
+}

src/app-layout/__integ__/awsui-applayout.test.ts

@@ -5,7 +5,7 @@ import useBrowser from '@cloudscape-design/browser-test-tools/use-browser';
 
 import createWrapper from '../../../lib/components/test-utils/selectors';
 import { viewports } from './constants';
-import { getUrlParams, Theme } from './utils';
+import { getUrlParams, testIf, Theme } from './utils';
 
 import testutilStyles from '../../../lib/components/app-layout/test-classes/styles.selectors.js';
 
@@ -197,4 +197,15 @@ describe.each(['classic', 'refresh', 'refresh-toolbar'] as Theme[])('%s', theme
       await expect(page.getNavPosition()).resolves.toEqual(navBefore);
     })
   );
+
+  testIf(theme === 'refresh-toolbar')(
+    'should keep header visible and in position while scrolling',
+    setupTest({ pageName: 'multi-layout-with-table-sticky-header' }, async page => {
+      const tableWrapper = createWrapper().findTable();
+      const { top: headerOldOffset } = await page.getBoundingBox(tableWrapper.findHeaderSlot().toSelector());
+      await page.windowScrollTo({ top: 200 });
+      const { top: headerNewOffset } = await page.getBoundingBox(tableWrapper.findHeaderSlot().toSelector());
+      expect(headerOldOffset).toEqual(headerNewOffset);
+    })
+  );
 });

src/app-layout/visual-refresh-toolbar/index.tsx

@@ -1,6 +1,6 @@
 // Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
-import React, { useEffect, useImperativeHandle, useState } from 'react';
+import React, { useEffect, useImperativeHandle, useLayoutEffect, useRef, useState } from 'react';
 
 import { useStableCallback } from '@cloudscape-design/component-toolkit/internal';
 
@@ -9,6 +9,7 @@ import { SplitPanelSideToggleProps } from '../../internal/context/split-panel-co
 import { fireNonCancelableEvent } from '../../internal/events';
 import { useControllable } from '../../internal/hooks/use-controllable';
 import { useIntersectionObserver } from '../../internal/hooks/use-intersection-observer';
+import { useMergeRefs } from '../../internal/hooks/use-merge-refs';
 import { useMobile } from '../../internal/hooks/use-mobile';
 import { useUniqueId } from '../../internal/hooks/use-unique-id';
 import { useGetGlobalBreadcrumbs } from '../../internal/plugins/helpers/use-global-breadcrumbs';
@@ -78,6 +79,8 @@ const AppLayoutVisualRefreshToolbar = React.forwardRef<AppLayoutProps.Ref, AppLa
     const [notificationsHeight, setNotificationsHeight] = useState(0);
     const [navigationAnimationDisabled, setNavigationAnimationDisabled] = useState(true);
     const [splitPanelAnimationDisabled, setSplitPanelAnimationDisabled] = useState(true);
+    const [isNested, setIsNested] = useState(false);
+    const rootRef = useRef<HTMLDivElement>(null);
 
     const [toolsOpen = false, setToolsOpen] = useControllable(controlledToolsOpen, onToolsChange, false, {
       componentName: 'AppLayout',
@@ -432,16 +435,45 @@ const AppLayoutVisualRefreshToolbar = React.forwardRef<AppLayoutProps.Ref, AppLa
       placement.inlineSize,
     ]);
 
+    /**
+     * Returns true if the AppLayout is nested
+     * Does not apply to iframe
+     */
+    const getIsNestedInAppLayout = (element: HTMLElement | null): boolean => {
+      let currentElement: Element | null = element?.parentElement ?? null;
+
+      // this traverse is needed only for JSDOM
+      // in real browsers the globalVar will be propagated to all descendants and this loops exits after initial iteration
+      while (currentElement) {
+        if (getComputedStyle(currentElement).getPropertyValue(globalVars.stickyVerticalTopOffset)) {
+          return true;
+        }
+        currentElement = currentElement.parentElement;
+      }
+
+      return false;
+    };
+
+    useLayoutEffect(() => {
+      if (!hasToolbar) {
+        setIsNested(getIsNestedInAppLayout(rootRef.current));
+      }
+    }, [hasToolbar]);
+
     return (
       <>
         {/* Rendering a hidden copy of breadcrumbs to trigger their deduplication */}
         {!hasToolbar && breadcrumbs ? <ScreenreaderOnly>{breadcrumbs}</ScreenreaderOnly> : null}
         <SkeletonLayout
-          ref={intersectionObserverRef}
+          ref={useMergeRefs(intersectionObserverRef, rootRef)}
           style={{
-            [globalVars.stickyVerticalTopOffset]: `${verticalOffsets.header}px`,
-            [globalVars.stickyVerticalBottomOffset]: `${placement.insetBlockEnd}px`,
             paddingBlockEnd: splitPanelOpen && splitPanelPosition === 'bottom' ? splitPanelReportedSize : '',
+            ...(hasToolbar || !isNested
+              ? {
+                  [globalVars.stickyVerticalTopOffset]: `${verticalOffsets.header}px`,
+                  [globalVars.stickyVerticalBottomOffset]: `${placement.insetBlockEnd}px`,
+                }
+              : {}),
             ...(!isMobile ? { minWidth: `${minContentWidth}px` } : {}),
           }}
           toolbar={