FG UI 1.2 theme laboratory

Themes 1.2

Built-in Light, Dark and System themes plus theme-package and preference surfaces.

FG UI 1.2 Stable
IMPLEMENTED IN FG UI 1.2 Stable

This page uses only the exact FG UI 1.2 Stable CSS and JavaScript.

Built-in theme switching

Light preserves the 1.1-compatible default; Dark and System are explicit 1.2 choices using the same FGUI component contracts.

FG UI 1.3 Theme Composition is now in development

Hybrid and local Light/Dark surface work is tested separately so the 1.2 Stable theme contract remains clear.

Open 1.3 Lab

Light

Default FG UI appearance and backwards-compatibility baseline.

Dark

Semantic-token dark surface treatment without changing component contracts.

Theme package compatibility

Theme manifests are token-only and registered by the host; Core performs no downloads.

FG UI 1.2.x compatible
Saved theme preference

The explicit selection is stored locally only after the user chooses a theme.

Opt-in
Theme preview
Preview without committing
FGUI surface preview

Theme packages change semantic tokens, not component contracts.

Theme package

Package readiness

Validate manifest metadata and compatibility before the host activates a package.

Manifest valid