Full-screen hamburger mobile menu

The “Menu” button keeps the same name and announces its state with aria-expanded; its three lines rotate into a cross. When it opens, focus moves to the first link, Tab and Shift+Tab cycle through the links, the call button and the cross, and the rest of the page becomes inert: screen readers included, nothing escapes the menu. Escape or the cross close the menu and return focus to the button; choosing a link closes it too. Page scrolling is locked while it is open. At the bottom, a box offers a direct call with the opening hours. Without JavaScript, the links stay displayed under the bar. Light and dark, AA contrast, and with prefers-reduced-motion the menu appears without animation.