Custom style for last post on page

Hello there,

I recently read this article https://www.elledoesit.com/on-the-computer/wordpress-tip-add-a-divider-after-all-but-last-post about modifying the loop to change how the last post on a page is displayed. In the tutorial however it shows you how to add a html tag to the last post (like a break for example) and i was wondering whether there would be a way to apply a different css class using the same method? I’m not particularily skilled with php so any help would be greatly appreciated!

Many thanks
Dan