Broken CSS url

[Knofan]

Hey Guys

Im have been struggling with policy violaions for Merchant center and we are turning every stone at the moment. I ran Dr. Link Check on my site and ran into several links that are broken. All of them raise 404´s and they are all links to asset. I have a few questions:

How important are this in the eyes of google that a ccs url is broken? 
How do i fix this problem? The asset is located somewhere inside shopify but i cant find it. 

Cheers lads and ladies!