[Bug]: Core Styles Adding Unremovable Gap Between Header and Content

[bobmatyas]

Quick summary

Default CSS adds gap between header and content that can't be removed.

Tested with Twenty Twenty Two theme.

Steps to reproduce

1. Create a template
2. Add header
3. Add block such as a "Cover Block" that you want to line up against header with post content
4. Observe gap between blocks

What you expected to happen

I shouldn't have a gap between elements or if there is, I should be able to edit it without CSS.

I can't edit without CSS because core styles are applied:

.wp-site-blocks > * + * {
  margin-block-start: var( --wp--style--block-gap );
}

What actually happened

There is a gap that can't be removed between header and site content.

Editor View:

Frontend:

Context

I encountered this while doing FSE testing to build a custom "post in a series" view

Browser

Mozilla Firefox

Simple/Atomic

Simple

Other notes

Can't be fixed on plans without CSS editing.

Reproducibility

Consistent

Severity

All

Available workarounds?

Yes, easy to implement

Workaround details

Can use this in Custom CSS:

.wp-site-blocks > * + * {
    margin-block-start: 0;
}

[edequalsawesome]

Came up in 35997697-hc

[jordesign]

Closing this to consolidate into #64438