fix: Keep the notification popup visible / centered (#2702)

- Closes: #2693

tests/utils/shadow-root.test.ts

@@ -0,0 +1,30 @@
+import { describe, expect, it } from 'vitest';
+
+import { getShadowRootHost } from '../../src/utils/shadow-root';
+
+// @vitest-environment jsdom
+describe('getShadowRootHost', () => {
+  it('should return the host of the shadow root the element lives in', () => {
+    const host = document.createElement('div');
+    host.attachShadow({ mode: 'open' });
+
+    const element = document.createElement('span');
+    host.shadowRoot?.append(element);
+
+    expect(getShadowRootHost(element)).toBe(host);
+  });
+
+  it('should return null for an element in the light DOM', () => {
+    const element = document.createElement('span');
+    document.body.append(element);
+    try {
+      expect(getShadowRootHost(element)).toBeNull();
+    } finally {
+      element.remove();
+    }
+  });
+
+  it('should return null for an element that is not connected', () => {
+    expect(getShadowRootHost(document.createElement('span'))).toBeNull();
+  });
+});