Add csslint for frontend linting.

Gruntfile.js

@@ -105,6 +105,8 @@ module.exports = function(grunt) {
     grunt.registerTask('feLint', [
         // ECMAScript
         'newer:eslint:frontend',
+        // CSS
+        'newer:csslint:frontend',
         // HTML.
         'newer:htmllint'
     ]);

grunt-config/csslint.js

@@ -0,0 +1,10 @@
+'use strict';
+
+module.exports = {
+    frontend: {
+        options: {
+            import: 2
+        },
+        src: ['<%= accountant.frontend.src %>/css/*.css']
+    }
+};

package.json

@@ -20,6 +20,7 @@
     "grunt-contrib-clean": "~1.0",
     "grunt-contrib-concat": "~1.0",
     "grunt-contrib-connect": "~1.0",
+    "grunt-contrib-csslint": "^2.0.0",
     "grunt-contrib-cssmin": "~1.0",
     "grunt-contrib-uglify": "~2.0",
     "grunt-contrib-watch": "~1.0",