How to add custom CSS for Content Views (free) version?

Sometimes, you want to add custom CSS for Content Views output.
In Pro version, there is a Custom CSS field in Content Views >> Settings page where you can add custom CSS easily.
In Free version, you can create and activate child theme, then add custom CSS to file style.css of your child theme.
You also can install a custom plugin to add custom CSS to your site. Or you can add this code to file functions.php of your active theme:

// Content Views - add custom CSS
add_action( 'wp_head', 'cv_theme_custom_style' );
function cv_theme_custom_style() {

Best regards,