Use concat to add license banner to css file.

Gruntfile.coffee

@@ -7,17 +7,18 @@ module.exports = (grunt) ->
   grunt.initConfig
     pkg: grunt.file.readJSON("package.json")
     comments: """
-/*************************************************************************
-* Chosen, a Select Box Enhancer for jQuery and Prototype
-* by Patrick Filler for Harvest, http://getharvest.com
-*
-* Version <%= pkg.version %>
-* Full source at https://github.com/harvesthq/chosen
-* Copyright (c) 2011 Harvest http://getharvest.com
-*
-* MIT License, https://github.com/harvesthq/chosen/blob/master/LICENSE.md
-* This file is generated by `grunt build`, do not edit it by hand.
-*************************************************************************/\n
+/*!
+Chosen, a Select Box Enhancer for jQuery and Prototype
+by Patrick Filler for Harvest, http://getharvest.com
+
+Version <%= pkg.version %>
+Full source at https://github.com/harvesthq/chosen
+Copyright (c) 2011 Harvest http://getharvest.com
+
+MIT License, https://github.com/harvesthq/chosen/blob/master/LICENSE.md
+This file is generated by `grunt build`, do not edit it by hand.
+*/
+\n
 """
     minified_comments: "/* Chosen #{version_tag()} | (c) 2011-2013 by Harvest | MIT License, https://github.com/harvesthq/chosen/blob/master/LICENSE.md */\n"
 
@@ -30,6 +31,9 @@ module.exports = (grunt) ->
       proto:
         src: ["public/chosen.proto.js"]
         dest: "public/chosen.proto.js"
+      css:
+        src: ["public/chosen.css"]
+        dest: "public/chosen.css"
 
     coffee:
       options:
@@ -52,15 +56,13 @@ module.exports = (grunt) ->
     compass:
       chosen_css:
         options:
-          banner: "<%= comments %>"
-          sassDir: "sass"
-          cssDir: "public"
           specify: ['sass/chosen.scss']
 
     cssmin:
       minified_chosen_css:
         options:
           banner: "<%= minified_comments %>"
+          keepSpecialComments: 0
         src: 'public/chosen.css'
         dest: 'public/chosen.min.css'