Can't set global background color for Post Template

[tellthemachines]

Description

Trying to set a background color for the Post Template block in global styles has no effect due to some overly-specific styling in the block CSS.

That was added in #37941 as a workaround for global styles for the List block bleeding into any other block that uses a ul (the same problem stands un-worked-around in the Navigation block)

The sustainable solution here would be to add a classname to the List block so we can attach global styles to it without contaminating other blocks with lists in their markup. My suggestion is revisiting #12420. Cc @carolinan who did some work on it previously!

Step-by-step reproduction instructions

1. In global styles panel, under blocks > Post Template, try adding a background color.
2. Save and verify that it has no effect in the editor or in the front end.

Screenshots, screen recording, code snippet

No response

Environment info

No response

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

Yes

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

Yes

[ramonjd]

I just came across this today.

It looks as if the .wp-block-post-template.wp-block-post-template CSS rule is overwriting the global styles block rule :where(.wp-block-post-template):

.wp-block-post-template.wp-block-post-template {
    background: none;
}

:where(.wp-block-post-template) {
    background-color: var(--wp--preset--color--foreground);
}

This change —

https://github.com/WordPress/gutenberg/blob/trunk/packages/block-library/src/post-template/style.scss#L8-L11

— was introduced a couple of years ago in #37941 but it seems to deliberately unset background colors.

I'm guessing we could delete it now that the Post Template block has color supports? @jasmussen @ntsekouras if you can remember that far back 😄

[tellthemachines]

Good timing, I had fixing this on my list for today now that #56469 is merged 😄

[ntsekouras]

I'm guessing we could delete it now that the Post Template block has color supports? @jasmussen @ntsekouras if you can remember that far back 😄

Yeah, the reason was mainly coming from the list block, but with #56469 merged the problem is not there.

I'm not sure whether we should remove it or adjust it a bit, because in general if theme devs add styles for ul, I don't think they would expect to affect Query Loop block too.

[tellthemachines]

I'm not sure whether we should remove it or adjust it a bit, because in general if theme devs add styles for ul, I don't think they would expect to affect Query Loop block too.

There are multiple blocks using list elements; Navigation is another one. I think theme devs usually take them into account when styling lists, so it shouldn't be a problem.