Suggestion to Add font-display: swap; for Better Font Loading

Hey there!

I noticed that the font files for Source Sans 3 and Source Code Pro don't include the `font-display: swap;` property in their CSS. Adding this would improve font loading by using **fallback** fonts until the preferred ones are ready, which can help prevent "invisible text" during slow font loading for users with slow internet connection.

This will help enhance performance let me know what you think!

Thanks!