Because you are including it independently, and not including it in your application.css
. The default for the asset pipeline is to compile applicaiton.css/application.js
and anything that is included in those files.
/*
* This is a manifest file that'll be compiled into application.css, which will include all the files
* listed below.
*
* Any CSS and SCSS file within this directory, lib/assets/stylesheets, vendor/assets/stylesheets,
* or any plugin's vendor/assets/stylesheets directory can be referenced here using a relative path.
*
* You're free to add application-wide styles to this file and they'll appear at the bottom of the
* compiled file so the styles you add here take precedence over styles defined in any styles
* defined in the other CSS/SCSS files in this directory. It is generally better to create a new
* file per style scope.
*
*= require_tree .
*= require c3
*= require purecss
*= require_self
*= require pure_css_reset
*/
If you want it to be seperate and not compiled into the one monolithic file, being called from your stylesheet_link_tag
, you have to manually add it to the precompile array.
http://guides.rubyonrails.org/asset_pipeline.html#precompiling-assets is a good reference.