title: Div still has margin even with margin: 0;
body: <p>I am trying to make a div with no margin around it (for a header across the page). I tried this:</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
      &lt;head&gt;
          &lt;title&gt;&lt;/title&gt;
          &lt;style&gt;
          .test {
              height: 100px;
              margin: 0;
              background-color: #000000;
          }
          &lt;/style&gt;
      &lt;/head&gt;
      &lt;body&gt;
          &lt;div class="test"&gt;&amp;nbsp;&lt;/div&gt;
      &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>but the div still has a margin around it. What am I doing wrong? Thanks for your help!</p>