title: How to change the background-color of a Bootstrap card-header?
body: <p>I'm trying to change the <code>background-color</code> of a bootstrap <code>card-header</code>, but when I add <code>background-color: #00AA9E</code> it seems to somehow destroy the look of the header..? Has anyone ever seen this before? Does it have something to do with the fact that the card is nested? Is it a bug in bootstrap?</p>
  <p><a href="https://i.stack.imgur.com/29I27.png" rel="nofollow noreferrer">Before  <code>background-color: #00AA9E</code></a></p>
  <p><a href="https://i.stack.imgur.com/BTNIE.png" rel="nofollow noreferrer">After  <code>background-color: #00AA9E</code></a></p>