Navigation Block: Submenus hidden by subsequent blocks (z-index issue) when Navigation is inside a Cover block

[philnick206]

Quick summary

Navigation blocks that are placed inside a Cover block and use submenus will have the submenus overlapped/hidden by subsequent blocks on the page.

Steps to reproduce

1. Create a Header that uses a Cover block and has a Navigation block inside (many common header patterns do this)
2. Add several menu items with submenu items to the menu
3. Add several Group blocks with content/patterns immediately after the Header/Cover block containing the Navigation

What you expected to happen

The Navigation submenus should always be visible on desktop screens

What actually happened

The Navigation submenus are hidden on desktop (ok on mobile in my testing)

Impact

Most (> 50%)

Available workarounds?

No but the platform is still usable

If the above answer is "Yes...", outline the workaround.

No response

Platform (Simple and/or Atomic)

No response

Logs or notes

Reported in 8600675-zd-a8c

[jartes]

📌 REPRODUCTION RESULTS

• Tested on Simple – Replicated
• Tested on Atomic – Replicated
• Replicable outside of Dotcom – Yes

📌 FINDINGS/SCREENSHOTS/VIDEO

• This is coming from Core, and it's already reported here: https://github.com/WordPress/gutenberg/issues/53857

📌 ACTIONS

• Triaged
• Lowering priority from High to Low
• Adding Core Fix Needed tag.

[ClassicRKR27]

@jartes I'm actually concerned that this issue has expanded beyond the Cover block.

I have a user here who is experiencing the same issue: 8627130-zd-a8c

But when I tried to remove it from the Cover block, that still wasn't enough - I had to completely remove it from the Header and all nested elements in order to get it to work, I've provided screenshots below:

I'm sure it's related to the issue that you mentioned, but something seems to have changed and it's happening in more conditions now.

[github-actions[bot]]

Support References

This comment is automatically generated. Please do not edit it.

• [ ] 8600675-zen
• [ ] 8627130-zen

[ClassicRKR27]

Just wanted to update that @mxhassani was able to find a CSS solution (at least for the Assembler theme):

header.wp-block-template-part .wp-block-cover {
  overflow: visible;
  z-index: 99999;
}

[philnick206]

Just wanted to update that @mxhassani was able to find a CSS solution (at least for the Assembler theme):

header.wp-block-template-part .wp-block-cover {
  overflow: visible;
  z-index: 99999;
}

That workaround worked great for 8600675-zd-a8c

Thanks for sharing!

[ramonjd]

Hmmm, looks to be caused by the overflow rules on the cover block:

https://github.com/WordPress/gutenberg/blob/2f939a7f9047ed9b632ac4fb0d593d0cf9588ce9/packages/block-library/src/cover/style.scss#L10-L14

But those same rules are required for sticky positioning. 🤔 cc @andrewserong in case there's extra context here.

[andrewserong]

But those same rules are required for sticky positioning. 🤔 cc @andrewserong in case there's extra context here.

I think they might have been added originally to handle border radius (so that the background is properly clipped to the radius of the border). The switch to clip instead of hidden was added for support for sticky positioning. The rule has been there for a long time now, so I'm not sure what a decent fix could be, unless there's a way for the rule to apply in more of a conditional way, only when it's needed, somehow? The hard thing there would be for us to know if border radius is being applied, given that could be set globally.

Unfortunately the main thing that comes to mind is that the Cover block isn't an ideal block to use for anything that would involve popovers (considering its issues with overflow here). Is there a reason why folks are using Cover blocks for their headers instead of a Group block? I.e. if it's about background images, the Group block now has pretty comprehensive background image support. If it's about being able to add an overlay color, though, then perhaps it highlights that it'd be good for Group blocks to be able to support overlays, I wonder?

[supernovia]

This might be a duplicate or likeness of this issue: https://github.com/Automattic/wp-calypso/issues/75439

[renatho]

This might be a duplicate or likeness of this issue: #75439

I just checked this one, and it seems there's another issue here related to overflow in the cover block. So the original solution doesn't fix the submenus. It needs some more investigation to check the implications of removing the overflow and possible workarounds.