Integrate Grained.JS into Shopify (Whole page)

[j2021c]

Hello,

We're looking at adding grained.js into our site. We want it to add noise over the whole page. 

This runs on an ID of a div etc - But I'm guessing for the whole site we'd have to use the Body tag? But how do we add an ID to the Body to act like a div does with this? 

Example of noise - https://godaytrip.com

Or if anyone knows of any other ways to do this using CSS etc. 

Believe 'Grained' uses a ::before tag but when adding this to the MainContent it goes behind the content and when adding above, it disables all links etc. 

Thanks for any help! 

[Upwords]

Did you ever figure this out?