This extension operates entirely locally within your browser. It does not collect, store, or transmit any personal data or browsing activity whatsoever.

All CSS modifications happen directly in your browser based on your settings and the bundled CSS file. No internet connection (beyond the browser's own sync mechanism if used) is required or utilized by the extension for its core functionality.

The only data saved is your preferred thumbnail count setting for the YouTube homepage layout. This setting is stored using the browser's standard storage.sync API, which means the setting might sync across your devices if you are logged into Firefox Sync, but the extension itself does not send this data to any external servers or third parties.