Cross-Origin Resource Sharing (CORS)
Table of contents
Cross-Origin Resource Sharing (CORS) is an HTTP-header based mechanism that allows a server to indicate any origins (domain, scheme, or port) other than its own from which a browser should permit loading resources. More details
You can set your Cross-Origin Resource Sharing header configuration yourself in the dashboard of a site, under the "Technical" tab in your site settings.
Note that these settings are specific to a site, and not synced automatically from the theme to each child site.