### Goal Add a **"Go to the top of the page"** link at the bottom of every page, for keyboard and screen reader users. ### Why On a long page (the About page, the Elements results, a gymnast with many elements) a keyboard or screen reader user has to tab or read back through everything to get to the navigation. A link at the end that goes straight to the start saves that. It is a usability aid for the keyboard and screen reader users the site must work for (universal design). ### How it should work - One shared component, put once in `App.tsx` after the page content, so every page gets it and no page has to add it. - It is **not seen** by sighted users, but is read by screen readers (`sr-only`). A sighted keyboard user sees it when it has the focus (`focus:not-sr-only`), like the "Skip to main content" link. - When it is used it scrolls to the top and puts the focus on the first thing that can be reached, which is the "Skip to main content" link. A plain `#` link would only scroll and leave the focus at the bottom. - It must not change the address or the history. - It uses the theme colors only, so it reads in light and dark mode. ### Done when - [ ] The link is at the end of every page (Elements, element page, Gymnasts, Gymnast, Calculator, About, Log in, Not found). - [ ] It is not visible until it has the focus, and it is visible, with a focus outline, when it has. - [ ] Using it scrolls to the top and moves the focus to the first focusable element. - [ ] A component test, and axe finds no violations with the link focused, in light and dark mode. - [ ] `docs/AI_USAGE.md` has an entry. _Text structured with Claude Code in discussion with Ronja._