CSS :target Pseudo-class

The :target pseudo-class selects an element if it's the target of the current URL fragment. This allows you to style elements when they're linked to, creating interactive effects for single-page navigation or in-page anchors.

p:target {
  background-color: violet;
}  
<a href="#p1">Anchor</a></li>
<p id="p1">
  This element will have a violet background when the user clicks on the anchor.
</p>