title: Making a div fit the initial screen
body: <p>I want to make a div fit the initial height and width of a users screen.</p>
  
  <p>I think the following crudely drawn diagram explain this better:</p>
  
  <p><img src="https://i.stack.imgur.com/ayGZM.png" alt="enter image description here"></p>
  
  <pre><code>#div
  {
   width: 100%;
   height: 100%;
  }
  </code></pre>
  
  <p>does not seem to work</p>