If your ReadyTheme did not come with the default Category Tree extension pre-installed, you can add it to your site by performing the following steps.
- Navigate to User Interface -> Global Settings -> Settings -> Category Tree Template
- Paste the content from category-tree.mvt.
- Create a new build subdirectory as
build/extensions/category-tree/
- Add _category-tree.scss to the directory.
- Update your
build/extensions/extensions.scss
file to include@import "category-tree/category-tree";