Why is the font of my website different on Convertize Editor?

It is possible that your website, once loaded in the Convertize Editor, displays a different type of font, or changes the size of your original content. Do not worry, this has not altered your website, it has simply changed for your view within the Editor.

If you are using Adobe Typekit

To display the correct font and size on the editor of Convertize, you will need to whitelist app.convertize.io in your Adobe Typekit.

To add or remove domains:

1. go to https://typekit.com/account/kits and launch the kit editor
2. Click Kit Settings in the upper right corner
3. Update the list of domain names
4. Save your settings
5. Click the Publish button at the bottom right of the kit editor to republish the kit

Please note that even if your website is displayed on Convertize with some small differences, when launching a test, the website will display the correct format to visitors.

Source: https://helpx.adobe.com/typekit/using/domains.html