Nearly a fixed hero section

I’m having an issue with this fixed hero section for a journal article:

https://preview.webflow.com/preview/pennyblack?utm_medium=preview_link&utm_source=designer&utm_content=pennyblack&preview=8c26ce8fb5ab621f4d3ddcf431c6d3ad&pageId=60954092552099e2765d85d9&itemId=60954092552099c67e5d865e&mode=preview

As you can see, the sections should all line up below this fixed header as you scroll. I’m lost, would appreciate an exchange with any advice!

Cheers!
Hamish


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