Simply download gridder and add it to your head, like this:
// index.html
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link href="path/to/gridder.css" rel="stylesheet">
</head>
<body>
<div id="app"></div>
</body>
</html>
Remember to add <meta name="viewport" content="width=device-width, initial-scale=1"> to the head aswell, to make sure the site scales correctly
Gridder is also available through this jsdelivr:
https://cdn.jsdelivr.net/npm/[email protected]/gridder.min.css
You can also add Gridder with NPM:
npm install gridder-css