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>