title: recommended css notation
body: <p>I have a div with an ID:</p>
  
  <pre><code>&lt;div id="main"&gt;
  </code></pre>
  
  <p>What's the correct (or difference) between</p>
  
  <pre><code>div#main {
  </code></pre>
  
  <p>and</p>
  
  <pre><code>#main {
  </code></pre>
  
  <p>Regards,</p>