Try resize workaround in tests for now

ui-tests/test/mobile.spec.ts

@@ -6,9 +6,10 @@ import path from 'path';
 import { expect } from '@playwright/test';
 
 import { test } from './fixtures';
+
 import { waitForKernelReady } from './utils';
 
-test.use({ autoGoto: false, viewport: { width: 524, height: 800 } });
+test.use({ autoGoto: false });
 
 test.describe('Mobile', () => {
   test('The layout should be more compact on the file browser page', async ({
@@ -30,12 +31,14 @@ test.describe('Mobile', () => {
       `${tmpPath}/${notebook}`
     );
     await page.goto(`notebooks/${tmpPath}/${notebook}`);
-    // TODO: investigate why this does not run the cells in Jupyter Notebook
-    // await page.notebook.run();
 
     // wait for the kernel status animations to be finished
     await waitForKernelReady(page);
 
+    // temporary workaround to trigger a toolbar resize
+    // TODO: investigate in https://github.com/jupyter/notebook/issues/6553
+    await page.setViewportSize({ width: 524, height: 800 });
+
     // force switching back to command mode to avoid capturing the cursor in the screenshot
     await page.evaluate(async () => {
       await window.jupyterapp.commands.execute('notebook:enter-command-mode');