Dark theme: Base button text is not visible

[romaricpascal]

Prerequisites

• I have searched for duplicate or closed issues
• I have validated any HTML to avoid common problems
• I have read the contributing guidelines

Describe the issue

The text of buttons using only the .btn class is not visible when using the dark theme.

Looking at the code, there's nothing that redefines --bs-btn-color back to the body color when switching themes, and on top of that, it's the .btn class that defines the --bs-btn-color so overrides any value we'd set in :root.

Reduced test cases

Run the documentation with npm run docs:serve and navigate to http://localhost:9001/docs/5.3/components/buttons/. The first example showing the base button will have no visible text.

What operating system(s) are you seeing the problem on?

Linux

What browser(s) are you seeing the problem on?

Firefox

What version of Bootstrap are you using?

5.3