title: How can I "dim" the rest of the web page when displaying a notification DIV?
body: <p>In my web app, I'm displaying a "notification" DIV.</p>
  
  <p>I would like to "dim" the rest of the page, so that the notification DIV stands out even more when displayed.</p>
  
  <p>Is there a reasonably easy way of doing so?</p>
  
  <p>This question is only concerned with visual effects, NOT the functionality of the rest of the page.</p>
  
  <p>Here is an example of the functionality I found elsewhere on the web (though in this case the dialog was a pop-up JS one, and not a DIV):</p>
  
  <p><img src="https://i.stack.imgur.com/ctp2V.png" alt="enter image description here"></p>