:target selects the HTML element with the attribute id that is the currently selected target of a <a href="…#tgt"> link.
<!DOCTYPE html>
<html>
<head>
<meta content="text/html;charset=utf-8" http-equiv="Content-Type">
<title>CSS - :target pseudo class</title>
<style>
:target {
background-color: navajowhite;
}
</style>
</head>
<body>
<p>This paragraph has no id.</p>
<p id='x'>This paragraph has has id=x and a <a href='#z'>link to z</a>.</p>
<p id='y'>This paragraph has has id=y.</p>
<p>This paragraph has no id and a <a href='#y'>link to y</a>.</p>
<p id='z'>This paragraph has has id=z</p>
</body>
</html>