SharePoint Add-In Issue?

Question

Hello All,

Here is a new task that I'm not able to understand.

Nowadays I'm trying to learn SharePoint Hosted Apps.

I created an App part in the application.

 

Now I have some challenges like. 

 

☺It is not validating my HTML 5 Control.

☺Not showing scroll in app part.

 

How to resolve these issues?

 

Help Needed!