That’s a bit delicate because the HTML isn’t standard. It’s written with a preprocessor (pug).
Usually, to reproduce a HTML+CSS pen, you reproduce the HTML structure in the designer (divs and classes), reproduce as much as you can of CSS in the designer too, and add what you can reproduce as custom CSS code.
But here, there’s a bit of magic on the HTML side. It generates quite a lenghty code if you inspect the source of the frame of the codepen result. I don’t even know if it’s feasible, or advisable, to try and reproduce this in webflow…