This theme is always active, and it is at the bottom of the theme
stack. See themes.
builtin_theme(dark = getOption("cli_theme_dark", "auto"))
Whether to use a dark theme. The cli_theme_dark option
can be used to request a dark theme explicitly. If this is not set,
or set to "auto", then cli tries to detect a dark theme, this
works in recent RStudio versions and in iTerm on macOS.
A named list, a CLI theme.