Wrong slash in Windows about grunt-css-urls HOT 2 CLOSED

|root
|  |-gruntfile.js
|  |-bower.json
|  |-Content
|  |  |-frontend.css
|  |  |-vendor
|  |  |  |-iCheck
|  |  |  |  |-square
|  |  |  |  |  |-blue.css
|  |  |  |  |  |[email protected]

.iradio_square-blue {
        background-image: url([email protected]);
        -webkit-background-size: 240px 24px;
        background-size: 240px 24px;
    }

@import './vendor/iCheck/square/blue.css';

module.exports = function(grunt) {
    grunt.initConfig({
/** prev code here**/
        cssUrls: {
            /* src *(required)*: The file location of the css with the @import rules. */
            src: "Content/frontend.css"
        },
        cssmin: {
            all: {
                files: {
                    './Content/activecontact.min.css': ['./Content/frontend.css']
                }
            }
        },
        copy: {
            main: {
                files: [
                  // iCheck
                  { expand: true, cwd: './bower_components/iCheck/skins/', src: ['**'], dest: './Content/vendor/iCheck/' },

                ]
            }
        }
    });

    grunt.registerTask("css", ["copy:main", "cssUrls", "cssmin"]);

    grunt.loadNpmTasks("grunt-contrib-concat");
    grunt.loadNpmTasks("grunt-contrib-uglify");

    grunt.loadNpmTasks("grunt-contrib-cssmin");
    grunt.loadNpmTasks('grunt-css-urls');
    grunt.loadNpmTasks('grunt-contrib-copy');
};

.iradio_square-blue {
        background-image: url(.\vendor\iCheck\square\[email protected]);
        -webkit-background-size: 240px 24px;
        background-size: 240px 24px;
    }