Enqueue stylesheet
***/
function kinsta_widget_enqueue_styles() {

wp_register_style( 'widget_cta_css', plugins_url( 'css/style.css', __FILE__ ) );
wp_enqueue_style( 'widget_cta_css' );

}
add_action( ‘wp_enqueue_scripts’, ‘kinsta_widget_enqueue_styles’ );