Set the href attribute to "style.css" to include the style sheet on the webpage.

<html>
<head>
<link href="style.css" rel="stylesheet">
<style>
.ad {
font-family: "Courier New";
}
</style>

</head>
<body>
<h3 class="ad">Software Engineer Wanted</h3>
<p class="ad">01010011 01101111 01100110</p>
</body>
</html>]]>

Make sure to add <link href="style.css" rel="stylesheet"> to your code.