# Dark mode

- `theme.defaultMode`: `light`, `dark` (default) or `system`; the front matter key
  `colorMode: light` overrides it. `theme: light` means the same thing and warns: `theme:` names a
  theme.
- Press **T** to switch; the choice is remembered by the browser.
- `theme.dark` holds the dark palette; Mermaid diagrams and Shiki code switch automatically.
- Inside a site, decks follow the site theme: use the switch in the header of this site.

<StoryEmbed slug="course" slide={7} />