add_filter( 'body_class', 'my_class_names' );
function my_class_names( $classes ) {
	global $current_user;
	$user_ID = $current_user->ID;
	
	if(is_array($current_user->roles)) {
		foreach($current_user->roles as $role) {
			$classes[] = 'user-id-' . $user_ID;
			$classes[]= 'user-role-' . $role;
		}
	}
	// return the $classes array
	return $classes;
}
 
add_filter('admin_body_class', function($classes) {
global $current_user;
$user_ID = $current_user->ID;
 
if(is_array($current_user->roles)) {
	foreach($current_user->roles as $role) {
		$classes .= "user-role-{$role} ";
		$classes .= "user-id-{$user_ID} ";
	}
}
	// return the $classes array
return rtrim($classes);
});