我对我应该使用什么来创建下拉菜单有些怀疑。只要看一下主题210，我就知道，

<div id="access" role="navigation">
              <?php /*  Allow screen readers / text browsers to skip the navigation menu and get right to the good stuff */ ?>
                <div class="skip-link screen-reader-text"><a href="#content" title="<?php esc_attr_e( \'Skip to content\', \'twentyten\' ); ?>"><?php _e( \'Skip to content\', \'twentyten\' ); ?></a></div>
                <?php /* Our navigation menu.  If one isn\'t filled out, wp_nav_menu falls back to wp_page_menu.  The menu assiged to the primary position is the one used.  If none is assigned, the menu with the lowest ID is used.  */ ?>
                <?php wp_nav_menu( array( \'container_class\' => \'menu-header\', \'theme_location\' => \'primary\' ) ); ?>
            </div>

在为下拉菜单编写css时，是否意味着我必须为Apprance->menus wp admin backend中创建的菜单编写一个css，并为wp admin backend中的导航不可用时编写一个css。