Description of problem:

I've registered a TechDocs addon in the subheader location in Red Hat Developer Hub and it seems there's a theme issue when viewed directly from the /docs page, where the background color for the subheader doesn't match the rest of the TechDocs page. When viewing from the "Docs" tab in a /catalog entity details page the colors seem to be fine. Happens both in light and dark theme.

I looked at the HTML and it seems that when viewing from the "Docs" entity tab, there's a parent article element that applies the background color but this element is missing when viewed directly in TechDocs page.

See discussion on Slack.

Prerequisites (if any, like setup, operators/versions):

Running RHDH 1.7 with TechDocs enabled and a TechDocs addon registered in the subheader location.

Steps to Reproduce

 Go to "Docs" page in the left navigation panel and display the TechDocs documentation for a given entity.

Actual results:

The background color for the subheader location doesn't match the rest of the TechDocs page (see screenshots).

Expected results:

The background color for the subheader location should match the rest of the TechDocs page.

Reproducibility (Always/Intermittent/Only Once):

Always.

Build Details:

RHDH Metadata RHDH Version: 1.7.2
Backstage Version: 1.39.1
Last Commit: redhat-developer/rhdh @ f36c0296
Build Time: 2025-09-22T23:24:09Z

Additional info (Such as Logs, Screenshots, etc):

I've attached screenshots showing TechDocs with a subheader addon registered viewed both from /docs and /catalog pages. I've also provided screenshots from RHDH 1.6, where it seems to look fine.