javascript - message: 'Unexpected token: punc (.)', while using uglify in grunt -

goal

my goal concatenate css,js files , minify of them. can minify concat.js, i'm struggling trying minify concat.css.

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gruntfile.js

module.exports = function(grunt) {     "use strict";      grunt.initconfig({          concat: {              js: {                 src: [                      'js/bootstrap.min.js',                     'js/jquery-1.10.2.min.js',                      'js/jquery.easypiechart.min.js',                     'js/jquery.isotope.min.js',                     'js/jquery.magnific-popup.min.js',                     'js/waypoints.min.js',                     'js/respond.min.js',                     'js/jquery.vegas.min.js',                     'js/modernizr-2.6.2.min.js',                     'js/jquery.nav.js',                     'js/html5shiv.js',                     'js/jquery.scrollto.js',                     'js/jquery.sticky.js',                     'js/jquery.validate.js',                     'js/main.js',                  ],                 dest: 'dist/concat.js'             },              css: {                 src: [                       'css/magnific-popup.css',                     'css/main.css',                     'css/xl.css',                     'css/lg.css',                     'css/md.css',                     'css/sm.css',                     'css/xs.css',                     'css/print.css',                     'css/bootstrap.min.css',                     'css/font-awesome.min.css',                  ],                 dest: 'dist/concat.css'             }         },          watch: {              js: {                  files: ['js/*.js'],                 task: ['concat:js']             },              css: {                 files: ['css/*.css'],                 task: ['concat:css']             }         },          uglify: {              js: {                 files: {                     'dist/minified.js': ['dist/concat.js']                 }             },              css: {                 files: {                     'dist/minified.css': ['dist/concat.css']                 }             }         }      });      grunt.loadnpmtasks('grunt-contrib-concat');     grunt.loadnpmtasks('grunt-contrib-uglify');     grunt.loadnpmtasks('grunt-contrib-watch');     grunt.registertask('default', ['concat', 'uglify']);  }; 

---

result

i concatenate css , js files succesfully, , they're generated @ :

• dist/concat.js
• dist/concat.css

then, can minify concat.js no problem, i'm struggling trying minify concat.css.

i kept getting error in bottom of terminal :

running "uglify:css" (uglify) task { message: 'unexpected token: punc (.)',   filename: 'concat.css',   line: 4, 

and line4 beginning of class : .mfp-bg {

can please give me little push here ? also, should perform minify after concatenation or other way around ? there better way ?

uglify minimising javascript only, not css.

if want minimise css can use cssmin task grunt instead.