After that, save your files, open your WordPress dashboard, browse to Appearance -> Themes, and activate your Twenty Twenty-One’s child theme.

When it comes to customizing the layout of your WordPress website, you have several options to add your custom CSS code. The Customizer’s Additional CSS panel could be enough for small changes.

But a child theme would be a better option if you have to make advanced customizations, or you need to export your code to different WordPress websites.

Let’s give it a try with simple customization: changing the default font stack.

Say you want to load a different font stack, or simply add your favorite font to the default Twenty Twenty-One font families.