HTML headings are inconsistent within and across dataset/group/org views

CKAN version

2.10

Describe the bug

HTML headings are inconsistent in several places, mostly where snippets are (re-)used at different hierarchy levels. This constitutes an accessibility issue as screen readers rely on HTML semantics.

Steps to reproduce

Open e.g. https://demo.ckan.org/dataset/sample-dataset-1 - it has 3 h1-headings:

one with the dataset name in the sidebar/secondary content
one with the dataset name in the primary content
one with the organization name in the sidebar/secondary content

Open https://demo.ckan.org/organization/sample-organization - it has 2 h1-headings

one with the organization name in the sidebar
one with "1 dataset found" in the primary content

(also applies to groups: https://demo.ckan.org/group/my-group)

However, the "X datasets found" snippet currently needs to use h1, as it is also used for e.g. the dataset search, e.g. https://demo.ckan.org/dataset/?q=sample&sort=score+desc%2C+metadata_modified+desc, which has no other headings.

Expected behavior

All CKAN pages follow HTML heading best practices in their headings:

there is exactly one h1 heading
every h(N+1) heading is a child of an h(N) heading

Implementation ideas

I found that the finnish open data portal has a nice CKAN skin that solves most (not all) of these issue (https://www.opendata.fi). I haven't looked into their implementation, but they found some nice conventions that CKAN could borrow from:

the tail (most specific part) of the bread crumbs is always the h1
that h1 is usually separately displayed above both the primary and secondary content

Besides that, requiring all snippets that set HTML headings to accept an 'parent heading level' (N) might be a way forward. All snippets could then set their heading levels algorithmically, starting at N+1.

Comments

I'm aware that this is a very complex issue, as any major changes might mess with customized installations in unexpected ways, especially if those rely on the current snippets.

I'm not sure how work has been done regarding the general UI overhaul in #7760, which will probably make this issue obsolete, but I felt it best to track this separately.

If it is in the interest of the community and maintainers, I can maybe get some funding for a PR.

ckan / ckan