The css seems to be there, but the html part isn’t showing up in your source code. Check your functions file and see if there is something like this –
wp_enqueue_script( 'epik-responsive-menu', get_bloginfo( 'stylesheet_directory' ) . '/js/responsive-menu.js',
The above line makes sure that the js file (located in the js folder in your theme) is activated. So check to see if that’s all there.