双色球开奖号码查询 www.tu23.com.cn Today we want to share an experimental drop-down menu with you. The main idea is to save space for menus that have a lot of content and sub-levels. Each sub-level in this menu will be shown in its own context, making the “parent” level disappear. This is done with subtle animations that are defined in separate animation classes. The menu is fluid so that it can be used easily in a responsive layout.