title: Angular 6 Mat-Dialog hides a part of the background webpage
body: <p>So, I have been using Mat-Dialog to show popups and dialogs, and I have just discovered this issue. A part of the background page(the page from which I open the modal) gets hidden when i scroll down on that page and try opening a dialog box. This issue is not found when the page is at the top. </p>
  
  <p><a href="https://i.stack.imgur.com/1e3is.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1e3is.png" alt="The problem I face when I scroll down on a webpage and open a dialog "></a></p>
  
  <p>I have no idea how to express this issue properly to you guys but, can y'all help me out? </p>
  
  <p>Much appreciated &amp; Thanks, 
  Ronny McNamara</p>