Describe the bug

This input CSS:

@layer b {
  body {
    color: green;
  }
}

@layer b;

results in the first @layer rule being deleted.

Expected behaviour

It should be equivalent to the output from this:

@layer b {
  body {
    color: green;
  }
}

@layer b {}

@layer rules without a block should be treated the same as if they had an empty block.

See this codepen for how it behaves in the browser: https://codepen.io/devongovett/pen/YzoxjPM

Steps to reproduce

see above

Version

latest

Preset

default

Environment

tested in the playground

Package details

https://cssnano.github.io/cssnano/playground/

Additional context

Related upstream bug in Next.js vercel/next.js#68476