Check out example codes for "media queries quick tutorial css". It will help you in understanding the concepts better.

Code Example 1

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<style>
body {
  background-color: lightgreen;
}

@media only screen and (max-width: 600px) {
  body {
    background-color: lightblue;
  }
}
</style>
</head>
<body>

<p>Resize the browser window. When the width of this document is 600 pixels or less, the background-color is "lightblue", otherwise it is "lightgreen".</p>

</body>
</html>

Code Example 2

/*
<a href="#">Linky Boo</a>
*/

a {
  color: red;
  text-decoration: none;
  text-transform: uppercase;
}

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