One page, no navigation: a username field and a "Next" button are shown; clicking it waits briefly, then reveals the password field via script with no page reload. Real sites do this (Google, Concur); recognizing it usually requires a manually scripted app that knows to wait before the password field appears.
Check it in DevTools: Elements panel: the password field is already sitting in the DOM at page load, just wrapped in a display:none div. Clicking "Next" only changes a style, it doesn’t trigger a new network request or page load.
Also active: Regenerate field IDs