<?php
function custom_posts_menu(){
 add_submenu_page('edit.php', 'HTML5', 'HTML5', 'manage_options', 'edit.php?category_name=html5' );
 add_submenu_page('edit.php', 'CSS3', 'CSS3', 'manage_options', 'edit.php?category_name=css3' );
}
function custom_pages_menu(){
 add_submenu_page('edit.php?post_type=page', 'HTML5', 'HTML5', 'manage_options', 'edit.php?category_name=html5' );
 add_submenu_page('edit.php?post_type=page', 'CSS3', 'CSS3', 'manage_options', 'edit.php?category_name=css3' );
}
add_action('admin_menu', 'custom_posts_menu');
add_action('admin_menu', 'custom_pages_menu');
?>