When you first load your landing page, you may notice that the fonts on your page will briefly load as the default browser fonts rather than the custom fonts that you’ve chosen.
This is due to the fact that your stylesheet takes longer to load than the html on your page. While your stylesheet loads, the browser will show the default fonts, and will apply the stylesheet as soon as it’s available.
This process is called Flash of Unstyled Content. Do you want to know more? Check out Wikipedia’s explanation of this process here.