<?php 

function add_user_role_body_class($classes) {
    // Check if the user is logged in
    if (is_admin() && is_user_logged_in()) {
        $user = wp_get_current_user();
        if (!empty($user->roles)) {
            // Add the first role as a class (WordPress allows multiple roles, usually the first one is primary)
            $classes .= ' user-role-' . sanitize_html_class($user->roles[0]);
        }
    }
    return $classes;
}
add_filter('admin_body_class', 'add_user_role_body_class');