title: How to use Marionette 3 Regions with existing page content? (e.g. server generated HTML)
body: <p>I'm trying to apply Marionette into our architecture as it seems to fit our current application better than other solutions. Our frontend HTML is mostly server-side generated using PHP and Twig (just to give some context).</p>
  
  <p>I'm now trying to use Marionette 3 Regions to achieve View compositions in a context where header, footer and generally the main content HTML are already there in the page.</p>
  
  <p>I couldn't find any example with this approach so I'm asking here if someone could give some advice.</p>
  
  <p>Thanks!</p>