Try avoid random build failure with postman.scss

nanoc/lib/mixin/inline.rb

@@ -10,7 +10,7 @@ module Mixin::Inline
   def inline_css(path)
     class_name = File.basename(path, File.extname(path))
     "<style class='css #{class_name}'>" \
-    "#{File.binread(File.join(build_dir, path))}" \
+    "#{items[path.sub('.css', '.scss')].compiled_content}" \
     "</style>"
   end
 end