This Learn WordPress tutorial covers the key files that make up a block theme behind-the-scenes, some important settings in your block theme’s theme.json that switch on important tools for you as a theme designer (appearanceTools, Layout, and Color: Palette), how to create and use a style guide in the site editor to help you plan your theme before the heavy lifting begins, and mentions some limitations of designing in the site editor new theme designers should be aware of (such as the use of images and fonts).