Why isn't scroll snapping working?

Hi Webflowers!

Scroll snapping is working (mostly) fine in the designer, but not on the published site.
Been scratching my head over this one for a while.

At the top of the page, in the introductory section, .prologue is set to {height:100vh} with {overflow:scroll} in order to enable scroll-snap, which should snap each div “.snap” keeping the .prologue_text in the center of the screen (100vh centered flexbox) as the user scrolls through.

I’m using the embedded styles method, and can see the desired effect happening in the designer - but in the page preview and the published page, it it not as intended.

Can anyone help me understand why?

Here is my Read-Only Link