Add supports of light-dark function

[wherewhere]

PR Checklist

• The changes have been tested (for bug fixes / features).
• Docs in NexT website have been added / updated (for features).

PR Type

• Bugfix.
• Feature.
• Improvement.
• Code style update (e.g. formatting, linting).
• Refactoring (no changes to functionality and APIs).
• Documentation.
• Translation.
• Other... Please describe:

What is the new behavior?

Add supports for new CSS feature light-dark:

2025-07-28.164052.mp4

The Code Block does not add light-dark support since the highlight.js and prism does not supports it. The disqusjs ether because the origin style seems not match to the dark one in this project.

@supports (color: light-dark(red, red)) is necessary because post-css will fallback it to weird implementation, which does not support prefers-color-scheme. The lightdark.check_supports can control the @supports block.

How to use?

In NexT _config.yml:

# Light-Dark Mode
lightdark:
  enable: true
  # Add @supports (color: light-dark(red, red)) check
  check_supports: true

[github-actions]

This pull request contains changes to the configuration file. Please make sure the documentation in NexT website is changed or added.
Please edit relevant source files here: https://github.com/next-theme/theme-next-docs/tree/master/source/docs and create a pull request with the changes here: https://github.com/next-theme/theme-next-docs/pulls