title: Overriding the underline from a bootstrap accordion's header
body: <p>I am playing with the Bootstrap accordion &amp; can't seem to be able to remove the underline/border which is displayed when the heading is open.</p>
  
  <p>The accordion-heading style doesn't seem to specify a border and I can't locate where it's coming from using an element inspector.</p>
  
  <p>The yellow highlighted line is what I am interested in (I have no trouble overriding the other borders.</p>
  
  <p><img src="https://i.stack.imgur.com/KAz5Z.png" alt="Header underline/border"></p>
  
  <p>Any tips?</p>