#8088 resolved on accepting var() in container queries, which was specified with ed383b5, which I think was intended to allow var() rather than custom properties.

So var() would be explicitly allowed in prose for size queries.

Style queries accept valid property declarations so var() is implicitly allowed.

This is not defined for scroll state queries.

WPT has tests for all three types of container queries:

• size queries
• style queries
• scroll state queries

Browsers are all green for style queries. It varies for the other types of queries.

Should <size-feature> and <scroll-state-feature> explicitly allow <var()> in their sub-productions? I guess it should only be allowed to substitute the feature value, not the feature name or the comparison operator.

Or should it be allowed in prose like in property values? For example:

The value of a custom property can be substituted into the value of a size feature with the var() function.

The value of a custom property can be substituted into the value of a scroll-state feature with the var() function.