title: CSS select parent element
body: <p>Supposing I have a HTML like this</p>
  
  <pre><code>&lt;label&gt;&lt;input type="radio" checked&gt;&lt;/label&gt;
  &lt;label&gt;&lt;input type="radio"&gt;&lt;/label&gt;
  </code></pre>
  
  <p>Question: how can I select the label of a checked radio in this case?</p>