Media queries are for different style rules for different size devices such as mobiles, desktops, etc.
You can try to run the following code to implement media queries with CSS3 −
Example
<html>
<head>
<style>
body {
background-color: lightpink;
}
@media screen and (max-width: 420px) {
body {
background-color: lightblue;
}
}
</style>
</head>
<body>
<p>If screen size is less than 420px, then it will show lightblue color,
or else it will show light pink color</p>
</body>
</html>