Feature request: Allow registering custom block styles for template parts

[carolinan]

I would like to be able to offer custom block styles for the site header, that are not available for other generic template parts.

register_block_style(
	'core/template-part/slug-that-matches-template-part-name',
	array(
		'name'  => 'prefix-box-shadow',
		'label' => __( 'Box shadow', 'textdomain' ),
	)
);

[justintadlock]

I've been thinking about this a bit. What about doing this based on the template part "area" too?

What I find myself needing is the ability to register styles for all header template parts and not just one.

[carolinan]

It is possible to register a style for template parts, but not area specific parts.
It may not be a good idea, since the user can not customize any template part styles. The block has no controls.

It may be a better option now to register style variations (section styles) for containers like groups, which are inside the template parts. The downside is that I have to click on "Edit" in the toolbar of the template part before selecting a style.

This json variation works when placed in the styles folder of a block theme:

{
	"$schema": "https://schemas.wp.org/trunk/theme.json",
	"version": 3,
	"title": "test",
	"slug": "header",
	"blockTypes": [ "core/template-part" ],
        "styles": {
		  "color": {
			  "background": "red"
		  }
	  }
}

But this does not work:

{
	"$schema": "https://schemas.wp.org/trunk/theme.json",
	"version": 3,
	"title": "test",
	"slug": "header",
	"blockTypes": [ "core/template-part/header" ],
	"styles": {
		"color": {
			"background": "red"
		}
	}
}

[carolinan]

@justintadlock shall I close this issue in favor of styling the container blocks?

[justintadlock]

I don't know. I still like the idea, but I've pretty much just been using block styles for nested container blocks for a long while now. I think that's probably just going to become the de facto standard method because themers and users haven't had a choice but to use an alternative solution.