Updated addon description wording
This is something that is not obvious because what you see in the browser is a web application. Here is a technical description of how the addon works.
On the Gramps side, the addon
exports a GEDCOM file from your database and runs a HTTP server inside Gramps that can send out the GEDCOM file.
Then, the addon opens your browser pointing to a web application hosted on GitHub pages. The web application is loaded in your browser. It is a “single page application” that once it is loaded it does not require an Internet connection to work (this is why you can open it from the browser’s cache even with WiFi turned off). After the web application is loaded it