title: :checked-functionality for li-element
body: <p>how can I simulate the behaviour of :checked for other elements then input-elements, like - this doesn't work of course, just for demonstrating purposes - for example here:</p>
  
  <pre><code>li{ background:red;}
  li:checked{
  background:orange;}
  </code></pre>
  
  <p>I actually want to use a plain css-solution and need to update the style of a li-element if this was clicked (<code>:active</code> does that, but solely for the moment of clicking it, I need it to keep the updated style as long as it's clicked again)</p>
  
  <p>Thanks</p>