Why doesn't Textual support ANSI themes?

Textual will not generate escape sequences for the 16 themeable ANSI colors.

This is an intentional design decision we took for the following reasons:

• Not everyone has a carefully chosen ANSI color theme. Color combinations which may look fine on your system, may be unreadable on another machine. There is very little an app author or Textual can do to resolve this. Asking users to simply pick a better theme is not a good solution, since not all users will know how.
• ANSI colors can't be manipulated in the way Textual can do with other colors. Textual can blend colors and produce light and dark shades from an original color, which is used to create more readable text and user interfaces. Color blending will also be used to power future accessibility features.

Textual has a design system which guarantees apps will be readable on all platforms and terminals, and produces better results than ANSI colors.

There is currently a light and dark version of the design system, but more are planned. It will also be possible for users to customize the source colors on a per-app or per-system basis. This means that in the future you will be able to modify the core colors to blend in with your chosen terminal theme.

!!! tip "Changed in version 0.80.0"

Textual added an `ansi_color` boolean to App. If you set this to `True`, then Textual will not attempt to convert ANSI colors. Note that you will lose transparency effects if you enable this setting.