为WordPress某个文章添加额外的样式

/*
为特定文章添加特定css最简单的方式.
*/
/*添加自定义CSS的meta box*/
add_action(‘admin_menu‘, ‘cwp_add_my_custom_css_meta_box‘);
/*保存自定义CSS的内容*/
add_action(‘save_post‘, ‘cwp_save_my_custom_css‘);
/*将自定义CSS添加到特定文章(适用于Wordpress中文章、页面、自定义文章类型等)的头部*/
add_action(‘wp_head‘,‘cwp_insert_my_custom_css‘);
function cwp_add_my_custom_css_meta_box() {
    add_meta_box(‘my_custom_css‘, ‘自定义CSS‘, ‘cwp_output_my_custom_css_input_fields‘, ‘post‘, ‘normal‘, ‘high‘);
    add_meta_box(‘my_custom_css‘, ‘自定义CSS‘, ‘cwp_output_my_custom_css_input_fields‘, ‘page‘, ‘normal‘, ‘high‘);
}
function cwp_output_my_custom_css_input_fields() {
    global $post;
    echo ‘<input type="hidden" name="my_custom_css_noncename" id="my_custom_css_noncename" value="‘.wp_create_nonce(‘custom-css‘).‘" />‘;
    echo ‘<textarea name="my_custom_css" id="my_custom_css" rows="5" cols="30" style="width:100%;">‘.get_post_meta($post->ID,‘_my_custom_css‘,true).‘</textarea>‘;
}
function cwp_save_my_custom_css($post_id) {
    if (!wp_verify_nonce($_POST[‘my_custom_css_noncename‘], ‘custom-css‘)) return $post_id;
    if (defined(‘DOING_AUTOSAVE‘) && DOING_AUTOSAVE) return $post_id;
    $my_custom_css = $_POST[‘my_custom_css‘];
    update_post_meta($post_id, ‘_my_custom_css‘, $my_custom_css);
}
function cwp_insert_my_custom_css() {
    if (is_page() || is_single()) {
        if (have_posts()) : while (have_posts()) : the_post();
        echo ‘<style type="text/css">‘.get_post_meta(get_the_ID(), ‘_my_custom_css‘, true).‘</style>‘;
        endwhile; endif;
        rewind_posts();
    }
}