bundle.css

/*@import url(http://fonts.googleapis.com/css?family=Chela+One);
@import url(http://fonts.googleapis.com/css?family=Architects+Daughter);
@import url(http://fonts.googleapis.com/css?family=Marck+Script);*/
 
/* Samsung Galaxy S4 Landscape */
/*@media screen (-webkit-min-device-pixel-ratio: 1.5),(min-resolution: 144dpi) and (device-width: 1920px) and (orientation: landscape){
}
*/
/* Samsung Galaxy S4 Portrait */
.maincontainer {
    width: 100%;
    height: 100px;
    margin: 0 auto;
    background-color: #D9534F;
    text-align: center;
}
 
/*@import url(http://fonts.googleapis.com/css?family=Chela+One);
@import url(http://fonts.googleapis.com/css?family=Architects+Daughter);
@import url(http://fonts.googleapis.com/css?family=Marck+Script);*/
 
/* Samsung Galaxy S4 Landscape */
/*@media screen (-webkit-min-device-pixel-ratio: 1.5),(min-resolution: 144dpi) and (device-width: 1920px) and (orientation: landscape){
}
*/
/* Samsung Galaxy S4 Portrait */
.maincontainer {
    width: 100%;
    height: 100px;
    margin: 0 auto;
    background-color: #D9534F;
    text-align: center;
}
 

Gruntfile.js

module.exports = function(grunt) {
  grunt.initConfig({
    concat: {
      css: {
        src: ['one.css', 'two.css'],
        dest: 'bundle.css'
      },
    },
  });
  grunt.loadNpmTasks('grunt-contrib-concat');
  grunt.registerTask('default', ['concat']);
};

one.css

/*@import url(http://fonts.googleapis.com/css?family=Chela+One);
@import url(http://fonts.googleapis.com/css?family=Architects+Daughter);
@import url(http://fonts.googleapis.com/css?family=Marck+Script);*/
 
/* Samsung Galaxy S4 Landscape */
/*@media screen (-webkit-min-device-pixel-ratio: 1.5),(min-resolution: 144dpi) and (device-width: 1920px) and (orientation: landscape){
}
*/
/* Samsung Galaxy S4 Portrait */
.maincontainer {
    width: 100%;
    height: 100px;
    margin: 0 auto;
    background-color: #D9534F;
    text-align: center;
}
 

two.css

/*@import url(http://fonts.googleapis.com/css?family=Chela+One);
@import url(http://fonts.googleapis.com/css?family=Architects+Daughter);
@import url(http://fonts.googleapis.com/css?family=Marck+Script);*/
 
/* Samsung Galaxy S4 Landscape */
/*@media screen (-webkit-min-device-pixel-ratio: 1.5),(min-resolution: 144dpi) and (device-width: 1920px) and (orientation: landscape){
}
*/
/* Samsung Galaxy S4 Portrait */
.maincontainer {
    width: 100%;
    height: 100px;
    margin: 0 auto;
    background-color: #D9534F;
    text-align: center;
}