Editing the navigation menu template in Drupal 8 I'm getting into Drupal with version 8, and trying to wrap my head around the template system.

I've created a theme with classy as a base theme. I would like to edit the markup for the navigation menu, adding two div's before the &lt;ul&gt;. I've copied the menu.html.twig file over from /core/themes/classy/templates/navigation into my-theme/templates/navigation.

I've added to div's right before the ul but they don't appear on the front-end. Is perhaps my template not being loaded? Or what would be the way to do this?
Simply needed to clear the cache... case closed!