title: I'm having problems showing leaflet map in a bootstrap tab
body: <p>I'm trying to put a leaflet map on a bootstrap tab, 
  but it's not working. Not showing at all or missing tiles and in the wrong position .</p>
  
  <p>Does anyone have an idea how to fix that?</p>
  
  <p>This is an example of the problem:
  <a href="https://i.stack.imgur.com/l8r4L.png" rel="nofollow noreferrer">missing tiles</a></p>
  
  <p>This is my code: <a href="https://gist.github.com/h3kr/991ac0ee5a88d0cecba27e91c886675e" rel="nofollow noreferrer">https://gist.github.com/h3kr/991ac0ee5a88d0cecba27e91c886675e</a> </p>