uncss on a rails landing page in < 15 min (initial config steps in comments)

config.diff

diff --git a/Gruntfile.js b/Gruntfile.js
index 53fe849..80ce14a 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -56,6 +56,16 @@ module.exports = function (grunt) {
         max_jshint_notifications: 5
       }
     },
+    uncss: {
+      gettingStarted: {
+        options: {
+          stylesheets: ['../../vendor/assets/bower_components/bootstrap/dist/css/bootstrap.css']
+        },
+        files: {
+          'app/assets/stylesheets/builds/getting-started.css': ['tmp/grunt/getting-started.html']
+        }
+      }
+    },
     watch: {
       lib: {
         options: {
@@ -100,6 +110,9 @@ module.exports = function (grunt) {
       },
       cleanGit: {
         command: 'git clean -fdx -- tmp public'
+      },
+      gettingStarted: {
+        command: 'curl -o tmp/grunt/getting-started.html http://localhost:3000/getting_started'
       }
     }
   });
@@ -110,6 +123,7 @@ module.exports = function (grunt) {
   grunt.loadNpmTasks('grunt-jsbeautifier');
   grunt.loadNpmTasks('grunt-concurrent');
   grunt.loadNpmTasks('grunt-shell');
+  grunt.loadNpmTasks('grunt-uncss');
   // grunt.loadNpmTasks('grunt-notify');
 
   // Default task.
@@ -124,5 +138,11 @@ module.exports = function (grunt) {
     'jshint'
   ]);
 
+  // Auto format files
+  grunt.registerTask('gettingStarted', [
+    'shell:gettingStarted',
+    'uncss:gettingStarted'
+  ]);
+
 
 };

diff --git a/app/assets/stylesheets/getting_started.scss b/app/assets/stylesheets/getting_started.scss
index f0ffc83..16733ab 100644
--- a/app/assets/stylesheets/getting_started.scss
+++ b/app/assets/stylesheets/getting_started.scss
@@ -1,5 +1,5 @@
 /*
- *= require bootstrap/dist/css/bootstrap.css
+ *= require builds/getting-started.css
  *= require_self
 */

Hi, I'm new to Grunt and I don't really understand how to use that with a rails app. Should I put the uncss: { } part in my grunt file ? If so, where ?

Thanks !