<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <title>Unsupported Browser</title>
    <meta http-equiv='content-type' content='text/html; charset=utf-8' />
    <meta name='viewport' content='initial-scale=1.0 maximum-scale=1.0'>
    <style>
        body {
            width: 600px;
            margin: 80px auto;
            font: normal 15px/25px sans-serif;
        }
    </style>
</head>

<body>
    <h1>Unsupported Browser</h1>
    <p>Sorry, the browser you're currently using is out of date and
        incompatible with geojson.io. Please upgrade
        to a modern browser in order to use the site.</p>
</body>

</html>
<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <title>Unsupported Browser or missing API</title>
    <meta http-equiv='content-type' content='text/html; charset=utf-8' />
    <meta name='viewport' content='initial-scale=1.0 maximum-scale=1.0'>
    <style>
        body {
            width: 600px;
            margin: 80px auto;
            font: normal 15px/25px sans-serif;
        }
    </style>
</head>

<body>
    <h1>Unsupported Browser or missing API</h1>
    <p>Sorry, the browser you're currently using do not seems to support WebGL. It could be disabled, or it could be because it is out of date. Please check if WebGL is supported and enabled, or supported, or upgrade
        to a modern browser in order to use the site.</p>
</body>

</html>

Add better error message when WebGL is not enabled
Add better error message when WebGL is not enabled