Glossary

Child Theme — WordPress子テーマ解説

WordPress子テーマは親テーマのデザインと機能を継承し、カスタマイズをアップデートから保護します。必要な場合と作成方法を解説します。

Definition

A child theme is a WordPress theme that inherits from another theme (the parent theme). It overrides selected styles and functions without directly editing the parent theme. This ensures customizations are preserved even after theme updates.

Why use a child theme?

If you edit a WordPress theme directly and the theme gets updated, all customizations are lost. A child theme solves this: your CSS and PHP customizations are in the child theme and won't be overwritten by parent theme updates. Mandatory for: custom CSS, modified theme code, custom template overrides.

Creating a child theme

A minimal child theme consists of a folder (e.g. `/wp-content/themes/your-theme-child/`) with a `style.css` that references the parent theme (`Template: parent-theme-folder`), and a `functions.php` that loads the parent CSS. Alternatively: plugins like Child Theme Configurator automate the process.

Child themes and block themes

With modern block themes (e.g. Twenty Twenty-Four), the need for child themes is reduced since styles can be customized via `theme.json` and the Full Site Editor — without code. Child themes remain relevant for PHP customizations, custom template parts, and complex feature extensions.

Frequently Asked Questions

Do I always need a child theme?

Not always. For pure content management without code customizations, no child theme is needed. As soon as you make custom CSS or PHP changes, you should use a child theme.

Does a child theme slow down my website?

No. A correctly set up child theme has no measurable impact on load time. It simply loads one additional CSS file.

How does anipage.io work with child themes?

anipage.io exports page content as Gutenberg block markup — independent of the theme used. The exported markup can be used in WordPress with any theme (including child themes).