Rails 3.1资产管道与PDFKit

I am using PDFkit with rails 3.1. In the past I was able to use the render_to_string function and create a pdf from that string. I then add the stylesheets as follows. My issue is that I have no idea how to access them from within the asset pipeline. (This is how I did it in rails 3.0)I am using PDFkit with rails 3.1. In the past I