How to Build a WordPress 7.0 Block Child Theme (with theme.json Boilerplate)

Is traditional CSS dead in modern enterprise web development? In this deep-dive tutorial, we explore the massive architectural shift behind WordPress 7.0 "Armstrong" and Full Site Editing (FSE). Instead of treating a theme as a fragile, human-readable cascading stylesheet, we look at theme.json as a centralized design token API and data layer, future-proofing front-end systems for performance, scalability, and machine-readability by AI agents.

We break down the technical concepts separating static pre-processors (Sass/SCSS) from runtime dynamic CSS variables, contrast the theme engine with enterprise systems like Adobe Experience Manager (AEM) Clientlibs, and build a production-ready block child theme from scratch.

💡 NOTE ON TIMESTAMPS: The first 27 minutes of this video is a rigorous technical deep dive into front-end architecture, theory, and logic. If you already understand the concepts and just want the fast step-by-step tutorial, skip straight to the 27:50 mark to see the live provisioning inside the Hostinger file manager.

⏱️ TIMESTAMPS
00:00 - The Paradigm Shift: Moving CSS to the Data Layer
00:39 - theme.json as a Centralized Design Token API
02:04 - Designing for 2026: Machine Readability & AI Agents
03:16 - What is a Dynamic CSS Variable? (Sass vs. Runtime Custom Properties)
05:40 - Enterprise Architecture: WordPress 7.0 vs. Adobe Experience Manager (AEM)
12:19 - Real World Project Introduction
13:03 - Overview of Required Theme Files
16:16 - Scalability Limits: When to Fallback from theme.json to style.css
19:37 - Mandatory Naming Conventions
20:30 - Enqueueing style.css for the Theme
21:58 - Dissect theme.json
26:14 - Understanding Palette Terms
27:50 - Live Build: Provisioning the Child Theme in Hostinger File Manager

🛠️ THEME METADATA CONFIGURATION (style.css Boilerplate)
/*
Theme Name: Twenty Twenty-Five Child
Template: twentytwentyfive
Version: 1.0.0
Text Domain: twentytwentyfive-child
*/

📂 GRAB THE COMPLETE CODE BOILERPLATE
If you want to copy the complete production-ready theme.json boilerplate featured in this video to jumpstart your own FSE builds, check out the companion blog post over at OneOffBoss: https://oneoffboss.com/how-to-create-a-wordpress-block-child-theme/

If you found this structural architectural deep dive helpful, hit the subscribe button for more videos focused on performance-driven development and systems automation. Drop any questions about your theme.json setups in the comments below!

Видео How to Build a WordPress 7.0 Block Child Theme (with theme.json Boilerplate) канала One Off Boss