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 you’ve chosen.
This is because 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 rendered fully.
This process is called Flash of Unstyled Content. Check out Wikipedia’s explanation of what flash unstyled content is, and how it works.
While some workarounds exist using JavaScript and CSS, adding a script can run the risk of increasing your page-load speed.
It may be worth checking in with a developer or web designer on some tips or custom scripts to prevent a Flash of Unstyled Content!