Theme inheritance and assets

Inheritance

The parents array lists ancestor theme slugs (furthest parent first). Twig loader order:

1. Core templates/
2. Active theme views/
3. Each parent from nearest to furthest

First matching template wins—child overrides parent.

theme_asset()

<link rel="stylesheet" href="{{ theme_asset('css/app.css') }}" />
<script src="{{ theme_asset('js/main.js') }}" defer></script>

URLs resolve under /theme-assets/… from the active theme's assets/ directory (with parent fallback rules).

Storefront asset boundary

Applies to all customer-facing paths: pages, content types, taxonomies, theme home.

Rules

1. Core marketing shell (public/root.twig) may use /css/styles.css and core JS.
2. Theme storefront must use theme_asset() only—never link /css/styles.css from themes/*/views/**.
3. Do not rely on marketing-only CSS class names without defining them in the theme.

Correct vs incorrect

Why it matters

• Portable themes swappable without marketing CSS coupling
• White-label and commercial theme packages stay self-contained
• Content archives stable when core marketing styles change

Layout lint

composer lint:twig-layouts
composer lint:twig-layouts --strict

Runs during composer test.

Homepage

GET / renders page/home.twig in the active theme unless Admin assigns a CMS page as public homepage.