Media queries allow CSS to adapt styles based on screen size.
Example:
<!DOCTYPE html>
<html>
<head>
<style>
body {
background-color: lightblue;
}
@media (max-width: 600px) {
body {
background-color: lightcoral;
}
}
</style>
</head>
<body>
<p>Resize the browser to see the background change.</p>
</body>
</html>