Hi info39,
How did you changed the font and the font size? Did you create a child theme before making any changes on it or not? If you have made a child theme then you are safe to upgrade to our pro version and if you have changed on the core file then all your customisation code will be lost. So we always recommended you to create a child theme before making any changes on it.
In our pro there there is also the features for google font and also the font size too.
Thank you!
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