title: Apply CSS rules to a nested class inside a div
body: <p>I don’t know exactly how to apply CSS to a nested element. Here is my example code, but I’m looking for a manual that explains all the rules:</p>
  
  <pre><code>&lt;div id="content"&gt;
    &lt;div id="main_text"&gt;
      &lt;h2 class="title"&gt;&lt;/h2&gt;
    &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>How can I apply CSS to only the class <code>title</code>, nested inside that particular <code>div</code>?</p>