<!DOCTYPE html>
<html>
<head>
<title>Title of the document</title>
<style>
section >:nth-last-child(2) {
background: lightgreen;
}
</style>
</head>
<body>
<section>
<div>Line №1</div>
<div>Line №2</div>
<div>Line №3</div>
<div>Line №4</div>
</section>
</body>
</html>