I'm finding the same result when I do a "git push" of the public folder.
Is why I'm currently attempting to use the git-deploy plugin, but that is also throwing an error for me (I've posted that in this Groups)
Not sure why the CSS isn't working without digging deeply into what is happening, I doubt has anything to do with the fact nodejs is used to build hexo. But it would be an issue if deploying to Gitlabs (I've posted about that, too in this Groups).