18_particles.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Particles</title>
    <style>
        html, body {
            margin: 0;
            height: 100%;
            padding: 0;
            background: #202030;
        }

        #contain {
            display: flex;
            justify-content: center;
            align-items: center;
            height: 100%;
        }
    </style>
</head>
<body>
    <div id="contain">
        <canvas id="particles" width="0px" height="0px"></canvas>
    </div>
    <script src="18_particles.js"></script>
</body>
</html>