Add User Role Class to Body

user-class-functions.php

<?php
/**
 * Add User Role Class to Body
 */
function print_user_classes() {
    if ( is_user_logged_in() ) {
        add_filter( 'body_class','class_to_body' );
        add_filter( 'admin_body_class', 'class_to_body_admin' );
    }
}
add_action( 'init', 'print_user_classes' );

// Add user role class to front-end body tag
function class_to_body( $classes ) {
    global $current_user;
    $user_role = array_shift( $current_user->roles );
    $classes[] = 'user_role_' . $user_role . ' ';
    return $classes;
}

// add 'class-name' to the $classes array
function class_to_body_admin( $classes ) {
    global $current_user;
    $user_role = array_shift( $current_user->roles );
    /* Adds the user id to the admin body class array */
    $user_ID = $current_user->ID;
    $classes = 'user_role_' . $user_role. ' ' . 'user-id-' . $user_ID ;
    return $classes;
    return 'user-id-' . $user_ID;
}