title: Transparent half circle cut out of a div
body: <p>I would like to make a transparent cut out half circle shape using only CSS3. The only requirement is that <strong>all the elements</strong> that form the shape <strong>must be black or transparent</strong>. </p>
  
  <p>I <strong>cannot use a black rectangle with a white circle</strong> on top of it because the half circle has to be transparent and let the background show through.</p>
  
  <p>Desired shape :</p>
  
  <p><img src="https://i.stack.imgur.com/EkDr6.png" alt="rectangle with cut out half circle"></p>