title: full-width background image limited height
body: <p>I want to get a full-screen background image but only the width, not the height, like <a href="https://www.edx.org/" rel="noreferrer">here</a></p>
  
  <p>I've been playing around with <code>background-size:cover;</code> but that covers the whole page - and I just want a certain height to be covered.</p>