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;
…
<!doctype html>
  <html lang="en">
    <head>
      <title>Mary's Maple Bar Fast-Baking Recipe</title>
      <title>Mary's Maple Bar Fast-Baking Recipe</title>
    </head>
  <body>
    …
  </body>
</html>