Don’t be too alarmed @ThomasC …
When you chose a font style it belongs to a font family. If you check your CSS you’ll notice that it calls up the font you have asked for, but if the User’s computer doesn’t have it onboard it then usually tries one or two backup font families. In your case your “Avenir Next” is backed up by “Sans Serif”, but if the User doesn’t have that then that is when issues arise.
Sparkle also uses Web Fonts which are imported Google Fonts. When this is setup instead of System Fonts your loading web page uses the font file generated when your Published your website to your hosting server. In other words all Users will see the same font on your loaded web pages, period.
Also to further confuse things you can also import fonts into Sparkle. So if you want to use say an unique scripted font that Google Fonts doesn’t have then you can import that into Sparkle and use it. When you Publish that font file goes up to your hosting server for everyone to use when loading your web pages.
Ok long winded but I hope it answers your question!
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