[EuiPopover] Fixed the z-index

[hetanthakkar]

Summary

Fixed issue #4756

Checklist

• Check against all themes for compatibility in both light and dark modes
• Checked in mobile
• Checked in Chrome, Safari, Edge, and Firefox
• Props have proper autodocs and playground toggles
• Added documentation
• Checked Code Sandbox works for the any docs examples
• Added or updated jest tests
• Checked for breaking changes and labeled appropriately
• Checked for accessibility including keyboard-only and screenreader modes
• A changelog entry exists and is marked appropriately

[kibanamachine]

Since this is a community submitted pull request, a Jenkins build has not been kicked off automatically. Can an Elastic organization member please verify the contents of this patch and then kick off a build manually?

[hetanthakkar]

The z-index of header is 1000 so I set the z-index of EuiPopver to be 999 instead of 2000

[elizabetdev]

jenkins test this

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_4818/

[elizabetdev]

Hi @hetanthakkar1,

Thanks for opening this PR but the EuiPopover should have a higher z-index than the EuiHeader or we might end up with this type of issue: #3398.

In some situations the popover might be too close to the top of the page and then it's impossible to read the content because the header (if fixed) can cover it.

So this "fix" can introduce a lot of issues and for this reason, I'm closing the PR. I guess issue #4756 shouldn't have been marked as a bug. Visually it looks like a bug but after some thought, it's not. 🤔