Smart App Banners

The banners on top of web apps that promote the native version of the app is controlled using a <meta> tag in the HTML:

<meta name="apple-itunes-app" content="app-id=1477376905, app-argument=https://github.com/" />

See the documentation on Promoting Apps with Smart App Banners . This only works for iOS Safari.

Example from GitHub:

Click to enlarge