The developing of index

Including:

• An interactive window in the align center of the index.
• Below the textual description at the top of the interactive window, the list of todos should appear.
• A tag refers to the residual amount of todos that needs to finish. (In the lower left-hand corner of the interactive window)
• Three buttons refer to 'All', 'Active', 'Completed'. Enable users to switch to the corresponding todos list. (In the align bottom of the interactive window)
• A button refers to 'Clear completed', which enable users to clear the tasks marked as completed in the list.
• The interactivity of the list. (Enable users to mark tasks in the list as completed or uncompleted, when a task is marked as completed, a strikeout and a tick should appear.)