Demo section showing dark fonts

[vyktoremario]

Summary

The design system has darkMode: ['class'] which means dark mode is controlled by a class. The issue is that --background and --foreground swap values in dark mode.

• Changed text colors to use the direct property (e.g var(--white))

[roomote]

Rooviewer Claude   See task on Roo Cloud

Review complete. No issues found.

The CSS changes correctly fix font visibility in the dark-background "Try it out" section by using appropriate color values.

_{Mention @roomote in a comment to request specific changes to this pull request or fix all unresolved issues.}