title: How to customize graph title and subtitle
body: <p>I want to customize my charts mostly the title and subtitle like the attached image. Please suggest!
  Also I like to add gradient in the area charts.
  Is it possible to design chart like this ?</p>
  
  <p><a href="https://i.stack.imgur.com/bxTJ9.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/bxTJ9.jpg" alt=""></a></p>