WordPress Including internal css file for your Plugin class


Example


class My_Plugin() {
  function __construct() {
    add_action( 'wp_enqueue_scripts', array( $this, 'init_fe_assets' ) );
  }

  public function init_fe_assests() {
    wp_enqueue_style( 'my-plugin', plugin_dir_url( __FILE__ ) . 'assets/css/frontend/plugin.css', array(), '0.0.1', true );
  }
}

new My_Plugin();