# File lib/premailer/rails/css_loaders/asset_pipeline_loader.rb, line 15
        def file_name(url)
          prefix = [
            ::Rails.configuration.relative_url_root,
            ::Rails.configuration.assets.prefix,
            '/'
          ].join
          URI(url).path
            .sub(/\A#{prefix}/, '')
            .sub(/-(\h{32}|\h{64})\.css\z/, '.css')
        end