Overlay scroll effect to a single section

Hello,

I tried adding the overlay scroll effect to a single section of my squarespace website, but for some reason, it applies to the whole page.

Desired effect: https://oriole-gar-h86y.squarespace.com/

My website: www.bluelinenp.com (I only want to add this effect to the first section)

I used this code:

<style>#page .page-section {position: sticky!important; top: 0px!important}
html {scroll-behavior: smooth}</style>