p {
width: 100px;
height: 50px;
padding: 20px;
border: 1px solid;
}
<!doctype html>
<html lang="en">
<head>
<title>Mary's Maple Bar Fast-Baking Recipe</title>
</head>
<body>

</body>
</html>
// Feature detection
if ('serviceWorker' in navigator) {
// Register a service worker
navigator.serviceWorker.register(
// A service worker JS file is separate
'service-worker.js'
);
// PaymentManager requires the service worker to be active.
// One simple method to activate a service worker is through
// a `ready` promise.
const registration = await navigator.serviceWorker.ready;