[css-cascade-6] What rules are invalid in @scope?

[cdoublev]

It is not clear whether @scope allows other CSS rules.

The syntax of the @scope rule is @scope [(<scope-start>)]? [to (<scope-end>)]? { <stylesheet> } where [...] <stylesheet> represents the scoped style rules.

https://drafts.csswg.org/css-cascade-6/#scope-syntax

All @scope examples in CSS Cascade 6 include (scoped) style rules.

Finally, the <stylesheet> production represents a list of rules. It is identical to <rule-list>, except that blocks using it default to accepting all rules that aren’t otherwise limited to a particular context.

For rules that use <stylesheet>, all rules are allowed by default, but the spec for the rule may define what types of rules are invalid inside the rule.

https://drafts.csswg.org/css-syntax-3/#rule-defs

[cdoublev]

Sorry, I missed this part:

Global name-defining at-rules such as @keyframes or @font-face or @layer that are defined inside @scope are valid but are not scoped or otherwise affected by the enclosing @scope rule. However, any style rules contained by such rules (e.g. within @layer) are scoped.

I guess the meaning of <stylesheet> represents the scoped style rules is that @scope only creates scope for style rules.