[css-page-3] Should `@page` declarations be hoisted?

Current version of Chrome and FF hoist declarations in @page:

const sheet = new CSSStyleSheet
sheet.replaceSync(`

  @page {
    @top-left {
      content: "green";
      color: green;
    }
    color: red;
  }

  style {
    @media {
      color: green;
    }
    color: red;
  }

`)

sheet.cssRules[0].cssText; // @page { color: red; @top-left { ...; color: green; } }
sheet.cssRules[1].cssText; // style { @media { color: green } color: red; }

If I am not mistaken, @page (with no page selector) and margin rules have the same specificity. So this might be unexpected, like in style rules.

Should they be wrapped in CSSNestedDeclarations whose style attribute is a CSSPageDescriptors?

Start by reading the issue's CSSStyleSheet example and comparing the described @page and margin-rule behavior with CSSNestedDeclarations and CSSPageDescriptors. The work is complete when the CSS Working Group resolves whether @page declarations should be hoisted and records the resulting behavior in the relevant specification.