flat

Flat

The default. Light and dark in one manifest on a neutral palette with a single blue accent, and every pair of tokens meets WCAG AA.

Using it

It ships with the platform. Pick it in the admin panel under Themes; the settings it declares appear as fields there, with no code to write.

Colours, fonts, radius and spacing as tokens, each one rendered as a field in the admin panel.
Light, dark or any named mode, with its own token values, in the same file.
Settings with labels and inputs that core renders for you, so a theme author writes no React for them.
Component overrides: replace the header, the footer or the hero and leave the rest alone.
Named slots a module can contribute into, declared by the theme rather than fixed by core.
Its own group in the admin sidebar, with a label and an icon.
Modules it suggests, shown as a banner the operator can dismiss. It never installs anything on its own.
Its own strings, in every locale, synced when the theme is activated.