fix: remove no longer needed z-index for root menu-bar items

[web-padawan]

Description

Fixes #7489

The code related to z-index was originally added when creating vaadin-menu-bar for Vaadin 14 due to the problem of handling clicks on root level menu items - see vaadin/vaadin-menu-bar#69. The issue about vaadin-menu-bar-button consuming clicks was apparently caused by native <button> with position: absolute used by V14 vaadin-button.

However, since in Vaadin 22 we changed <vaadin-button> to not use native <button> internally, these styles are no longer needed. Furthermore, removing them resolves the Firefox issue (which unfortunately can only be tested manually at the moment), so it seems like this rendering bug is a combination of container-type: size and z-index properties.

Type of change

• Bugfix

Note

I confirmed that z-index: 1 is still needed in V14 to allow clicks on root level items with the following example:

<vaadin-menu-bar></vaadin-menu-bar>

<script type="module">
  import '@vaadin/menu-bar';

  const anchor = document.createElement('a');
  anchor.setAttribute('href', 'https://example.com');
  anchor.textContent = 'Example';

  document.querySelector('vaadin-menu-bar').items = [
    {
      component: anchor,
    },
  ];
</script>

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[vaadin-bot]

Hi @web-padawan and @web-padawan, when i performed cherry-pick to this commit to 24.3, i have encountered the following issue. Can you take a look and pick it manually?
Error Message:
Error: Command failed: git cherry-pick d8ae511
error: could not apply d8ae511... fix: remove no longer needed z-index for root menu-bar items (#7743)
hint: After resolving the conflicts, mark them with
hint: "git add/rm ", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".

[vaadin-bot]

This ticket/PR has been released with Vaadin 24.5.0.beta2 and is also targeting the upcoming stable 24.5.0 version.