Product Landing Page (applying css)

Hi there, I’m struggling with the product landing page, I’m coding in vsc and pasting across to codepen but find that nothing works beyond the nav-bar in css ? I’ve kept the code pretty much the same and was going to start editing from completed backwards but can’t figure out why the css won’t apply. I’ve just tried a like for like codepen into a fresh codepen page, absolutely none of my code, just a codepen html paste, css paste and js paste and it still doesn’t look the same ? The css isn’t applying ?

oh ok, the codepen html analyzer says there is no linked stylesheet for the icons, but if I copied and pasted it into a new codepen like for like how are they not the same ?

Can you give us a link to your codepen?