### Source Peer feedback, collected in #167. Quote (translated): the dark theme does not follow the operating system setting on the first visit. ### Problem The theme toggle reads only `localStorage` in `App.tsx` and never checks `prefers-color-scheme`. A visitor whose system is in dark mode gets the light theme on the first visit. ### What to do - [ ] When nothing is stored under `theme`, start from `window.matchMedia('(prefers-color-scheme: dark)')`. - [ ] Keep the stored choice once the visitor has toggled the theme. - [ ] Decide whether the page follows later changes of the system setting while no choice is stored. - [ ] Add a test for both cases (nothing stored, and a stored choice that differs from the system). ### Done when - [ ] A first visit with a dark system opens in dark mode, and a stored choice always wins. _Comment made with Claude Code in discussion with Ronja_