Description

Gutenberg version Version 15.9.1
WordPress 6.2.2

For instance adding a background color to the Group block inside the Heading and having the Post Content block just below looks like this:

Backend. Header Group block contains a dark blue color. Post Content block shows a Cover block. There is a gap between the Cover block and the Header above it showing a white space.

Frontend with developer tools open. Shows the following code:

:where(.wp-site-blocks) > * {
    margin-block-start: 1.5rem;
    margin-block-end: 0;
}

Deactivating margin-block-start: 1.5rem will also remove the white space.

Please remove the margin-block-start: 1.5rem or atleast make it visible inside the UI so that we can adjust it there.
Having margins or padding one can not adjust inside the UI forces one to add custom CSS or perhaps adjust it through the theme.json file.

Step-by-step reproduction instructions

Screenshots, screen recording, code snippet

Environment info

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

No