Variant doesn't expand when inside a media query

[xt0rted]

What version of Tailwind CSS are you using?

v4.0.0

What build tool (or framework if it abstracts the build tool) are you using?

Astro 5.1.9
@tailwindcss/vite 4.0.0

What version of Node.js are you using?

v23.4.0

What browser are you using?

Chrome

What operating system are you using?

Windows

Reproduction URL

https://play.tailwindcss.com/11WjRHqAY2?file=css

Describe your issue

@variant dark will expand if it wraps @media, but not if it's inside it.

I'd expect this

@media (prefers-reduced-motion: reduce) {
  @variant dark {
    a {
      color: red;
    }
  }
}

to become this

@media (prefers-reduced-motion: reduce) {
  &:where(.dark, .dark *) {
    a {
      color: red;
    }
  }
}

but @variant dark remains in the output css.

[xt0rted]

My example looks to be fixed in 4.0.3, most likely due to #16129.