title: Input checked change body background colour using JS
body: <p>I have an input checkbox. I want to change all the body CSS of the HTML (white body-background and black text when unchecked, and black body-background and white text when checked).</p>
  
  <p>HTML:</p>
  
  <pre><code>  &lt;input id="nightmode" type="checkbox"&gt;Activate night mode
  </code></pre>