Local installation is a process of downloading pure-min.css file in a directory of your website, e.g. /css and then use the CSS file in your HTML page.
<html>
<head>
<title>The PURE.CSS Example</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="pure-min.css">
<style>
.grids-example {
background: rgb(250, 250, 250);
margin: 2em auto;
border-top: 1px solid yellow;
border-bottom: 1px solid red;
font-family: Consolas, 'Liberation Mono', Courier, monospace;
text-align: center;
}
</style>
</head>
<body>
<div class="grids-example">
<div class="pure-g">
<div class="pure-u-1-3"><p>First Column</p></div>
<div class="pure-u-1-3"><p>Second Column</p></div>
<div class="pure-u-1-3"><p>Third Column</p></div>
</div>
</div>
</body>
</html>