<?php
function hmbl_theme_color() {
    global $post;

    $color = hmbl_recursive_find_color($post->ID);

    if ($color != false) : ?>

        <style type="text/css" media="screen">
            .theme-color {
                color: <?php echo $color ?>;
            }
            .theme-background-color {
                background-color: <?php echo $color ?>;
            }
            .theme-border-color {
                border-color: <?php echo $color ?>;
            }
        </style>

    <?php endif;
}
add_action('wp_head', 'hmbl_theme_color');

function hmbl_recursive_find_color($post_id) {
    $use_color = get_field('theme_color_active', $post_id);

    if ($use_color == true) {
        return get_field('theme_color', $post_id);
    } else {
        $post = get_post($post_id);
        if (isset($post->post_parent) && $post->post_parent != 0) {
            return hmbl_recursive_find_color($post->post_parent);
        } else {
            return false;
        }
    }
}