body class according to number of published custom posts

add to functions.php

function wpc_body_class_section($classes) {  
    if (is_user_logged_in()) {        
        $classes[] = 'CUSTOMPOST-'.count_user_posts(get_current_user_id());
    } 

    return $classes;  
}  
add_filter('body_class','wpc_body_class_section');