To customize extension-related HTML and Sass files, you must use the override method. This involves placing copies of source HTML and Sass files from your Extras directory into your theme directory and making your customizations there. When you deploy your changes, the theme development tools detect the new files and initiate an override within the manifest.
Note:You cannot override asset files. To introduce new assets for your template customizations or extension overrides, add them as you would for any new files within the template directory, then reference the assets using the HTML and Sass helpers.