[slarse]

The theme is activated by defining the environment variable EXPERIMENTAL_BUT_LIGHT_THEME with any value. The reason it is prefixed "EXPERIMENTAL" is that this isn't the way we want to enable the theme, it's just a temporary way of enabling it.

To justify the need for this, here's the dark theme on a light background:

And here's the light theme on light background:

There are most certainly small pieces I've missed, but this at least makes the TUI significantly more usable on a light background. While not very evident from the screenshots, the context lines of the diff view were entirely invisible, for one.

[Copilot]

Pull request overview

Adds an experimental light theme option to the but CLI/TUI, toggled via the EXPERIMENTAL_BUT_LIGHT_THEME environment variable, including a matching light syntax-highlighting theme for the TUI details diff view.

Changes:

• Switch Theme::default() to choose between dark/light palettes based on EXPERIMENTAL_BUT_LIGHT_THEME, and introduce default_dark() / default_light() builders.
• Add a light Syntect theme (Monokai Extended Light.tmTheme) and select it for syntax highlighting in the TUI details view when the env var is set.
• Adjust white/gray foreground/background mapping for ANSI styling output.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
crates/but/src/theme.rs	Adds light theme defaults and selects light/dark palette at runtime via env var.
crates/but/src/command/legacy/status/tui/details/mod.rs	Adds light syntax theme asset loading and switches Syntect theme selection based on env var.
crates/but/assets/syntax-highlighting-themes/Monokai Extended Light.tmTheme	New light syntax-highlighting theme asset.
crates/but/assets/syntax-highlighting-themes/Monokai Extended License	Updates license notice to cover both dark and light theme files.